6.7 Integer Exponents and Scientific Notation

Use the Definition of a Negative Exponent

We saw that the Quotient Property for Exponents introduced earlier in this chapter, has two forms depending on whether the exponent is larger in the numerator or the denominator.

What if we just subtract exponents regardless of which is larger?

Let’s consider $\frac{x^{2}}{x^{5}}$ .

We subtract the exponent in the denominator from the exponent in the numerator.

$\begin{matrix} \frac{x^{2}}{x^{5}} \\ x^{2 - 5} \\ x^{−3} \end{matrix}$

We can also simplify $\frac{x^{2}}{x^{5}}$ by dividing out common factors:

Illustrated in this figure is x times x divided by x times x times x times x times x. Two xes cancel out in the numerator and denominator. Below this is the simplified term: 1 divided by x cubed.

This implies that $x^{−3} = \frac{1}{x^{3}}$ and it leads us to the definition of a negative exponent.

The negative exponent tells us we can re-write the expression by taking the reciprocal of the base and then changing the sign of the exponent.

Any expression that has negative exponents is not considered to be in simplest form. We will use the definition of a negative exponent and other properties of exponents to write the expression with only positive exponents.

For example, if after simplifying an expression we end up with the expression $x to the power −3$ , we will take one more step and write $\frac{1}{x^{3}}$ . The answer is considered to be in simplest form when it has only positive exponents.

In Example 1 we raised an integer to a negative exponent. What happens when we raise a fraction to a negative exponent? We’ll start by looking at what happens to a fraction whose numerator is one and whose denominator is an integer raised to a negative exponent.

	$\frac{1}{a^{− n}}$
Use the definition of a negative exponent, $a^{− n} = \frac{1}{a^{n}}$ .	$\frac{1}{\frac{1}{a^{n}}}$
Simplify the complex fraction.	$1 \cdot \frac{a^{n}}{1}$
Multiply.	$a^{n}$

This leads to the Property of Negative Exponents.

Suppose now we have a fraction raised to a negative exponent. Let’s use our definition of negative exponents to lead us to a new property.

**Table 6.4**
	${(\frac{3}{4})}^{−2}$
Use the definition of a negative exponent, $a^{− n} = \frac{1}{a^{n}}$ .	$\frac{1}{{(\frac{3}{4})}^{2}}$
Simplify the denominator.	$\frac{1}{\frac{9}{16}}$
Simplify the complex fraction.	$\frac{16}{9}$
But we know that $\frac{16}{9}$ is ${(\frac{4}{3})}^{2}$ .
This tells us that:	${(\frac{3}{4})}^{−2} = {(\frac{4}{3})}^{2}$

To get from the original fraction raised to a negative exponent to the final result, we took the reciprocal of the base—the fraction—and changed the sign of the exponent.

This leads us to the Quotient to a Negative Power Property.

Example 3

Simplify: ⓐ ${(\frac{5}{7})}^{−2}$ ⓑ ${(- \frac{2 x}{y})}^{−3} .$

ⓐ	${(\frac{5}{7})}^{−2}$
Use the Quotient to a Negative Exponent Property, ${(\frac{a}{b})}^{− n} = {(\frac{b}{a})}^{n}$ .
Take the reciprocal of the fraction and change the sign of the exponent.	${(\frac{7}{5})}^{2}$
Simplify.	$\frac{49}{25}$
ⓑ	${(- \frac{2 x}{y})}^{−3}$
Use the Quotient to a Negative Exponent Property, ${(\frac{a}{b})}^{− n} = {(\frac{b}{a})}^{n}$ .
Take the reciprocal of the fraction and change the sign of the exponent.	${(- \frac{y}{2 x})}^{3}$
Simplify.	$- \frac{y^{3}}{8 x^{3}}$

When simplifying an expression with exponents, we must be careful to correctly identify the base.

Example 4

Simplify: ⓐ $open parenthesis −3 close parenthesis to the power −2$ ⓑ $− 3 to the power −2$ ⓒ ${(- \frac{1}{3})}^{−2}$ ⓓ $− {(\frac{1}{3})}^{−2} .$

ⓐ Here the exponent applies to the base $−3$ .	$open parenthesis −3 close parenthesis to the power −2$
Take the reciprocal of the base and change the sign of the exponent.	$\frac{1}{{(−3)}^{−2}}$
Simplify.	$\frac{1}{9}$
ⓑ The expression $− 3 to the power −2$ means "find the opposite of $3 to the power −2$ ." Here the exponent applies to the base ${(- \frac{1}{3})}^{}$ .	$− 3 to the power −2$
Rewrite as a product with $-1$ .	$−1 \cdot 3^{−2}$
Take the reciprocal of the base and change the sign of the exponent.	$−1 \cdot \frac{1}{3^{2}}$
Simplify.	$- \frac{1}{9}$
ⓒ Here the exponent applies to the base ${(- \frac{1}{3})}^{}$ .	${(- \frac{1}{3})}^{−2}$
Take the reciprocal of the base and change the sign of the exponent.	${(- \frac{3}{1})}^{2}$
Simplify.	$9$
ⓓ The expression $− {(\frac{1}{3})}^{−2}$ means "find the opposite of ${(\frac{1}{3})}^{−2}$ ." Here the exponent applies to the base $(\frac{1}{3})$ .
Rewrite as a product with $-1$ .	$−1 \cdot {(\frac{1}{3})}^{−2}$
Take the reciprocal of the base and change the sign of the exponent.	$−1 \cdot {(\frac{3}{1})}^{2}$
Simplify.	$−9$

We must be careful to follow the Order of Operations. In the next example, parts (a) and (b) look similar, but the results are different.

Example 5

Simplify: ⓐ $4 \cdot 2^{−1}$ ⓑ ${(4 \cdot 2)}^{−1} .$

ⓐ Do exponents before multiplication.	$4 \cdot 2^{−1}$
Use $a^{− n} = \frac{1}{a^{n}}$ .	$4 \cdot \frac{1}{2^{1}}$
Simplify.	$2$
ⓑ	${(4 \cdot 2)}^{−1}$
Simplify inside the parentheses first.	$open parenthesis 8 close parenthesis to the power −1$
Use $a^{− n} = \frac{1}{a^{n}}$ .	$\frac{1}{8^{1}}$
Simplify.	$\frac{1}{8}$

When a variable is raised to a negative exponent, we apply the definition the same way we did with numbers. We will assume all variables are non-zero.

When there is a product and an exponent we have to be careful to apply the exponent to the correct quantity. According to the Order of Operations, we simplify expressions in parentheses before applying exponents. We’ll see how this works in the next example.

Example 7

Simplify: ⓐ $5 y to the power −1$ ⓑ $open parenthesis 5 y close parenthesis to the power −1$ ⓒ $open parenthesis −5 y close parenthesis to the power −1.$

ⓐ

	$5 y to the power −1$
Notice the exponent applies to just the base y. Take the reciprocal of y and change the sign of the exponent.	$5 \cdot \frac{1}{y^{1}}$
Simplify.	$\frac{5}{y}$

ⓑ

	$open parenthesis 5 y close parenthesis to the power −1$
Here the parentheses make the exponent apply to the base 5y. Take the reciprocal of 5y and change the sign of the exponent.	$\frac{1}{{(5 y)}^{1}}$
Simplify.	$\frac{1}{5 y}$

ⓒ

	$open parenthesis −5 y close parenthesis to the power −1$
The base here is −5y. Take the reciprocal of −5y and change the sign of the exponent.	$\frac{1}{{(−5 y)}^{1}}$
Simplify.	$\frac{1}{−5 y}$
Use $\frac{a}{− b} = - \frac{a}{b} .$	$- \frac{1}{5 y}$

With negative exponents, the Quotient Rule needs only one form $\frac{a^{m}}{a^{n}} = a^{m - n}$ , for $a not equal to 0$ . When the exponent in the denominator is larger than the exponent in the numerator, the exponent of the quotient will be negative.

Simplify Expressions with Integer Exponents

All of the exponent properties we developed earlier in the chapter with whole number exponents apply to integer exponents, too. We restate them here for reference.

Example 8

Simplify: ⓐ $x^{−4} \cdot x^{6}$ ⓑ $y^{−6} \cdot y^{4}$ ⓒ $z^{−5} \cdot z^{−3} .$

ⓐ

	$x^{−4} \cdot x^{6}$
Use the Product Property, $a^{m} \cdot a^{n} = a^{m + n} .$	$x^{−4 + 6}$
Simplify.	$x^{2}$

ⓑ

	$y^{−6} \cdot y^{4}$
Notice the same bases, so add the exponents.	$y^{−6 + 4}$
Simplify.	$y to the power −2$
Use the definition of a negative exponent, $a^{− n} = \frac{1}{a^{n}} .$	$\frac{1}{y^{2}}$

ⓒ

	$z^{−5} \cdot z^{−3}$
Add the exponents, since the bases are the same.	$z^{−5 - 3}$
Simplify.	$z to the power −8$
Take the reciprocal and change the sign of the exponent, using the definition of a negative exponent.	$\frac{1}{z^{8}}$

In the next two examples, we’ll start by using the Commutative Property to group the same variables together. This makes it easier to identify the like bases before using the Product Property.

Example 9

Simplify: $(m^{4} n^{−3}) (m^{−5} n^{−2}) .$

	$(m^{4} n^{−3}) (m^{−5} n^{−2})$
Use the Commutative Property to get like bases together.	$m^{4} m^{−5} \cdot n^{−2} n^{−3}$
Add the exponents for each base.	$m^{−1} \cdot n^{−5}$
Take reciprocals and change the signs of the exponents.	$\frac{1}{m^{1}} \cdot \frac{1}{n^{5}}$
Simplify.	$\frac{1}{m n^{5}}$

In the next two examples, we’ll use the Power Property and the Product to a Power Property.

Example 10

Simplify: $open parenthesis 6 k cubed close parenthesis to the power −2.$

	$open parenthesis 6 k cubed close parenthesis to the power −2$
Use the Product to a Power Property, ${(a b)}^{m} = a^{m} b^{m} .$	${(6)}^{−2} {(k^{3})}^{−2}$
Use the Power Property, ${(a^{m})}^{n} = a^{m \cdot n} .$	$6^{−2} k^{−6}$
Use the Definition of a Negative Exponent, $a^{− n} = \frac{1}{a^{n}} .$	$\frac{1}{6^{2}} \cdot \frac{1}{k^{6}}$
Simplify.	$\frac{1}{36 k^{6}}$

Example 11

Simplify: $open parenthesis 5 x to the power −3 close parenthesis squared.$

	$open parenthesis 5 x to the power −3 close parenthesis squared$
Use the Product to a Power Property, ${(a b)}^{m} = a^{m} b^{m} .$	$5 squared open parenthesis x to the power −3 close parenthesis squared$
Simplify 5² and multiply the exponents of x using the Power Property, ${(a^{m})}^{n} = a^{m \cdot n} .$	$25 \cdot x^{−6}$
Rewrite x⁻⁶ by using the Definition of a Negative Exponent, $a^{− n} = \frac{1}{a^{n}} .$	$25 \cdot \frac{1}{x^{6}}$
Simplify.	$\frac{25}{x^{6}}$

To simplify a fraction, we use the Quotient Property and subtract the exponents.

Convert from Decimal Notation to Scientific Notation

Remember working with place value for whole numbers and decimals? Our number system is based on powers of 10. We use tens, hundreds, thousands, and so on. Our decimal numbers are also based on powers of tens—tenths, hundredths, thousandths, and so on. Consider the numbers 4,000 and $0.004$ . We know that 4,000 means $4 times 1,000$ and 0.004 means $4 \times \frac{1}{1,000}$ .

If we write the 1000 as a power of ten in exponential form, we can rewrite these numbers in this way:

$\begin{matrix} 4,000 & 0.004 \\ 4 \times 1,000 & 4 \times \frac{1}{1,000} \\ 4 \times 10^{3} & 4 \times \frac{1}{10^{3}} \\ 4 \times 10^{−3} \end{matrix}$

When a number is written as a product of two numbers, where the first factor is a number greater than or equal to one but less than 10, and the second factor is a power of 10 written in exponential form, it is said to be in scientific notation.

It is customary in scientific notation to use as the $\times$ multiplication sign, even though we avoid using this sign elsewhere in algebra.

If we look at what happened to the decimal point, we can see a method to easily convert from decimal notation to scientific notation.

This figure illustrates how to convert a number to scientific notation. It has two columns. In the first column is 4000 equals 4 times 10 to the third power. Below this, the equation is repeated, with an arrow demonstrating that the decimal point at the end of 4000 has moved three places to the left, so that 4000 becomes 4.000. The second column has 0.004 equals 4 times 10 to the negative third power. Below this, the equation is repeated, with an arrow demonstrating how the decimal point in 0.004 is moved three places to the right to produce 4.

In both cases, the decimal was moved 3 places to get the first factor between 1 and 10.

$\begin{matrix} The power of 10 is positive when the number is larger than 1: & 4,000 = 4 \times 10^{3} \\ The power of 10 is negative when the number is between 0 and 1: & 0.004 = 4 \times 10^{−3} \end{matrix}$

Example 14

Write in scientific notation: $0.0052.$

The original number, $0.0052$ , is between 0 and 1 so we will have a negative power of 10.


Move the decimal point to get 5.2, a number between 1 and 10.
Count the number of decimal places the point was moved.
Write as a product with a power of 10.
Check.
$\begin{matrix} 5.2 \times 10^{−3} \\ 5.2 \times \frac{1}{10^{3}} \\ 5.2 \times \frac{1}{1000} \\ 5.2 \times 0.001 \end{matrix}$
$0.0052$

Convert Scientific Notation to Decimal Form

How can we convert from scientific notation to decimal form? Let’s look at two numbers written in scientific notation and see.

$\begin{matrix} 9.12 \times 10^{4} & 9.12 \times 10^{−4} \\ 9.12 \times 10,000 & 9.12 \times 0.0001 \\ 91,200 & 0.000912 \end{matrix}$

If we look at the location of the decimal point, we can see an easy method to convert a number from scientific notation to decimal form.

$\begin{matrix} 9.12 \times 10^{4} = 91,200 & 9.12 \times 10^{−4} = 0.000912 \end{matrix}$

This figure has two columns. In the left column is 9.12 times 10 to the fourth power equals 91,200. Below this, the same scientific notation is repeated, with an arrow showing the decimal point in 9.12 being moved four places to the right. Because there are no digits after 2, the final two places are represented by blank spaces. Below this is the text “Move the decimal point four places to the right.” In the right column is 9.12 times 10 to the negative fourth power equals 0.000912. Below this, the same scientific notation is repeated, with an arrow showing the decimal point in 9.12 being moved four places to the left. Because there are no digits before 9, the remaining three places are represented by spaces. Below this is the text “Move the decimal point 4 places to the left.”

In both cases the decimal point moved 4 places. When the exponent was positive, the decimal moved to the right. When the exponent was negative, the decimal point moved to the left.

The steps are summarized below.

Example 16

Convert to decimal form: $8.9 \times 10^{−2} .$


Determine the exponent, n, on the factor 10.
Since the exponent is negative, move the decimal point 2 places to the left.
Add zeros as needed for placeholders.

Multiply and Divide Using Scientific Notation

Astronomers use very large numbers to describe distances in the universe and ages of stars and planets. Chemists use very small numbers to describe the size of an atom or the charge on an electron. When scientists perform calculations with very large or very small numbers, they use scientific notation. Scientific notation provides a way for the calculations to be done without writing a lot of zeros. We will see how the Properties of Exponents are used to multiply and divide numbers in scientific notation.

Example 18

Divide. Write answers in decimal form: $\frac{9 \times 10^{3}}{3 \times 10^{−2}} .$

	$\frac{9 \times 10^{3}}{3 \times 10^{−2}}$
Separate the factors, rewriting as the product of two fractions.	$\frac{9}{3} \times \frac{10^{3}}{10^{−2}}$
Divide.	$3 \times 10^{5}$
Change to decimal form by moving the decimal five places right.	300,000

Key Concepts

Property of Negative Exponents
- If $n$ is a positive integer and $a not equal to 0$ , then $\frac{1}{a^{− n}} = a^{n}$
Quotient to a Negative Exponent
- If $a, b$ are real numbers, $b not equal to 0$ and $n$ is an integer, then ${(\frac{a}{b})}^{− n} = {(\frac{b}{a})}^{n}$
To convert a decimal to scientific notation:
1. Move the decimal point so that the first factor is greater than or equal to 1 but less than 10.
2. Count the number of decimal places, $n$ , that the decimal point was moved.
3. Write the number as a product with a power of 10. If the original number is:
  - greater than 1, the power of 10 will be $10 to the power n$
  - between 0 and 1, the power of 10 will be $10 to the power − n$
4. Check.
To convert scientific notation to decimal form:
1. Determine the exponent, $n$ , on the factor 10.
2. Move the decimal nplaces, adding zeros if needed.
  - If the exponent is positive, move the decimal point $n$ places to the right.
  - If the exponent is negative, move the decimal point $| n |$ places to the left.
3. Check.

Section Exercises

Practice Makes Perfect

Use the Definition of a Negative Exponent

In the following exercises, simplify.

ⓐ $4 to the power −2$ ⓑ $10 to the power −3$

ⓐ $3 to the power −4$ ⓑ $10 to the power −2$

ⓐ $\frac{1}{81}$ ⓑ $\frac{1}{100}$

ⓐ $5^{- 3}$ ⓑ $10 to the power −5$

ⓐ $2 to the power −8$ ⓑ $10 to the power −2$

ⓐ $\frac{1}{256}$ ⓑ $\frac{1}{100}$

ⓐ $\frac{1}{c^{−5}}$ ⓑ $\frac{1}{3^{−2}}$

ⓐ $\frac{1}{c^{−5}}$ ⓑ $\frac{1}{5^{−2}}$

ⓐ $c to the power 5$ ⓑ 25

ⓐ $\frac{1}{q^{−10}}$ ⓑ $\frac{1}{10^{−3}}$

ⓐ $\frac{1}{t^{−9}}$ ⓑ $\frac{1}{10^{−4}}$

ⓐ $t to the power 9$ ⓑ 10000

ⓐ ${(\frac{5}{8})}^{−2}$ ⓑ ${(- \frac{3 m}{n})}^{−2}$

ⓐ ${(\frac{3}{10})}^{−2}$ ⓑ ${(- \frac{2}{c d})}^{−3}$

ⓐ $\frac{100}{9}$ ⓑ $- \frac{c^{3} d^{3}}{8}$

ⓐ ${(\frac{4}{9})}^{−3}$ ⓑ ${(- \frac{u^{2}}{2 v})}^{−5}$

ⓐ ${(\frac{7}{2})}^{−3}$ ⓑ ${(- \frac{3}{x y^{2}})}^{−3}$

ⓐ $\frac{8}{343}$ ⓑ $- \frac{x^{3} y^{6}}{27}$

ⓐ ${(- 5)}^{- 2}$ ⓑ $− 5 to the power −2$ ⓒ ${(- \frac{1}{5})}^{−2}$ ⓓ $− {(\frac{1}{5})}^{−2}$

ⓐ $open parenthesis −7 close parenthesis to the power −2$ ⓑ $- 7^{- 2}$ ⓒ ${(- \frac{1}{7})}^{−2}$ ⓓ $− {(\frac{1}{7})}^{−2}$

ⓐ $\frac{1}{49}$ ⓑ $- \frac{1}{49}$ ⓒ 49 ⓓ $−49$

ⓐ $− 3 to the power −3$ ⓑ ${(- \frac{1}{3})}^{−3}$ ⓒ $− {(\frac{1}{3})}^{−3}$ ⓓ $open parenthesis −3 close parenthesis to the power −3$

ⓐ $− 5 to the power −3$ ⓑ ${(- \frac{1}{5})}^{−3}$ ⓒ $− {(\frac{1}{5})}^{−3}$ ⓓ $open parenthesis −5 close parenthesis to the power −3$

ⓐ $- \frac{1}{125}$ ⓑ $−125$ ⓒ $−125$ ⓓ $- \frac{1}{125}$

ⓐ $3 \cdot 5^{−1}$ ⓑ ${(3 \cdot 5)}^{−1}$

ⓐ $2 \cdot 5^{−1}$ ⓑ ${(2 \cdot 5)}^{−1}$

ⓐ $\frac{2}{5}$ ⓑ $\frac{1}{10}$

ⓐ $4 \cdot 5^{−2}$ ⓑ ${(4 \cdot 5)}^{−2}$

ⓐ $3 \cdot 4^{−2}$ ⓑ ${(3 \cdot 4)}^{−2}$

ⓐ $\frac{3}{16}$ ⓑ $\frac{1}{144}$

ⓐ $m to the power −4$ ⓑ $open parenthesis x cubed close parenthesis to the power −4$

ⓐ $b to the power −5$ ⓑ $open parenthesis k squared close parenthesis to the power −5$

ⓐ $\frac{1}{b^{5}}$ ⓑ $\frac{1}{k^{10}}$

ⓐ $p to the power −10$ ⓑ ${(q^{6})}^{−8}$

ⓐ $s to the power −8$ ⓑ ${(a^{9})}^{−10}$

ⓐ $\frac{1}{s^{8}}$ ⓑ $\frac{1}{a^{90}}$

ⓐ $7 n to the power −1$ ⓑ $open parenthesis 7 n close parenthesis to the power −1$ ⓒ $open parenthesis −7 n close parenthesis to the power −1$

ⓐ $6 r to the power −1$ ⓑ $open parenthesis 6 r close parenthesis to the power −1$ ⓒ $open parenthesis −6 r close parenthesis to the power −1$

ⓐ $\frac{6}{r}$ ⓑ $\frac{1}{6 r}$ ⓒ $- \frac{1}{6 r}$

ⓐ $open parenthesis 3 p close parenthesis to the power −2$ ⓑ $3 p to the power −2$ ⓒ $−3 p to the power −2$

ⓐ $open parenthesis 2 q close parenthesis to the power −4$ ⓑ $2 q to the power −4$ ⓒ $−2 q to the power −4$

ⓐ $\frac{1}{16 q^{4}}$ ⓑ $\frac{2}{q^{4}}$ ⓒ $- \frac{2}{q^{4}}$

Simplify Expressions with Integer Exponents

In the following exercises, simplify.

ⓐ $b^{4} b^{−8}$ ⓑ $r^{−2} r^{5}$ ⓒ $x^{−7} x^{−3}$

ⓐ $s^{3} \cdot s^{−7}$ ⓑ $q^{−8} \cdot q^{3}$ ⓒ $y^{−2} \cdot y^{−5}$

ⓐ $\frac{1}{s^{4}}$ ⓑ $\frac{1}{q^{5}}$ ⓒ $\frac{1}{y^{7}}$

ⓐ $a^{3} \cdot a^{−3}$ ⓑ $a \cdot a^{3}$ ⓒ $a \cdot a^{−3}$

ⓐ $y^{5} \cdot y^{−5}$ ⓑ $y \cdot y^{5}$ ⓒ $y \cdot y^{−5}$

ⓐ 1 ⓑ $y to the power 6$ ⓒ $\frac{1}{y^{4}}$

$p^{5} \cdot p^{−2} \cdot p^{−4}$

$x^{4} \cdot x^{−2} \cdot x^{−3}$

$\frac{1}{x}$

$(w^{4} x^{−5}) (w^{−2} x^{−4})$

$(m^{3} n^{−3}) (m^{−5} n^{−1})$

$\frac{1}{m^{2} n^{4}}$

$(u v^{−2}) (u^{−5} v^{−3})$

$(p q^{−4}) (p^{−6} q^{−3})$

$\frac{1}{p^{5} q^{7}}$

$(−6 c^{−3} d^{9}) (2 c^{4} d^{−5})$

$(−2 j^{−5} k^{8}) (7 j^{2} k^{−3})$

$- \frac{14 k^{5}}{j^{3}}$

$(−4 r^{−2} s^{−8}) (9 r^{4} s^{3})$

$(−5 m^{4} n^{6}) (8 m^{−5} n^{−3})$

$- \frac{40 n^{3}}{m}$

$open parenthesis 5 x squared close parenthesis to the power −2$

$open parenthesis 4 y cubed close parenthesis to the power −3$

$\frac{1}{64 y^{9}}$

$open parenthesis 3 z to the power −3 close parenthesis squared$

$open parenthesis 2 p to the power −5 close parenthesis squared$

$\frac{4}{p^{10}}$

$\frac{t^{9}}{t^{−3}}$

$\frac{n^{5}}{n^{−2}}$

$n to the power 7$

$\frac{x^{−7}}{x^{−3}}$

$\frac{y^{−5}}{y^{−10}}$

$y to the power 5$

Convert from Decimal Notation to Scientific Notation

In the following exercises, write each number in scientific notation.

57,000

340,000

$3.4 \times 10^{5}$

8,750,000

1,290,000

$1.29 \times 10^{6}$

0.026

0.041

$4.1 \times 10^{−2}$

0.00000871

0.00000103

$1.03 \times 10^{−6}$

Convert Scientific Notation to Decimal Form

In the following exercises, convert each number to decimal form.

$5.2 times 10 squared$

$8.3 times 10 squared$

830

$7.5 \times 10^{6}$

$1.6 \times 10^{10}$

16,000,000,000

$2.5 \times 10^{−2}$

$3.8 \times 10^{−2}$

0.038

$4.13 \times 10^{−5}$

$1.93 \times 10^{−5}$

0.0000193

Multiply and Divide Using Scientific Notation

In the following exercises, multiply. Write your answer in decimal form.

$(3 \times 10^{−5}) (3 \times 10^{9})$

$(2 \times 10^{2}) (1 \times 10^{−4})$

0.02

$(7.1 \times 10^{−2}) (2.4 \times 10^{−4})$

$(3.5 \times 10^{−4}) (1.6 \times 10^{−2})$

$0.0000056$

In the following exercises, divide. Write your answer in decimal form.

$\frac{7 \times 10^{−3}}{1 \times 10^{−7}}$

$\frac{5 \times 10^{−2}}{1 \times 10^{−10}}$

500,000,000

$\frac{6 \times 10^{4}}{3 \times 10^{−2}}$

$\frac{8 \times 10^{6}}{4 \times 10^{−1}}$

20,000,000

Everyday Math

The population of the United States on July 4, 2010 was almost 310,000,000. Write the number in scientific notation.

The population of the world on July 4, 2010 was more than 6,850,000,000. Write the number in scientific notation

$6.85 \times 10^{9}$ .

The average width of a human hair is 0.0018 centimeters. Write the number in scientific notation.

The probability of winning the 2010 Megamillions lottery was about 0.0000000057. Write the number in scientific notation.

$5.7 \times 10^{−9}$

In 2010, the number of Facebook users each day who changed their status to ‘engaged’ was $2 \times 10^{4}$ . Convert this number to decimal form.

At the start of 2012, the US federal budget had a deficit of more than $$ 1.5 \times 10^{13}$ . Convert this number to decimal form.

15,000,000,000,000

The concentration of carbon dioxide in the atmosphere is $3.9 \times 10^{−4}$ . Convert this number to decimal form.

The width of a proton is $1 \times 10^{−5}$ of the width of an atom. Convert this number to decimal form.

0.00001

Health care costs The Centers for Medicare and Medicaid projects that consumers will spend more than $4 trillion on health care by 2017.

ⓐ Write 4 trillion in decimal notation.
ⓑ Write 4 trillion in scientific notation.

Coin production In 1942, the U.S. Mint produced 154,500,000 nickels. Write 154,500,000 in scientific notation.

$1.545 \times 10^{8}$

Distance The distance between Earth and one of the brightest stars in the night star is 33.7 light years. One light year is about 6,000,000,000,000 (6 trillion), miles.

ⓐ Write the number of miles in one light year in scientific notation.
ⓑ Use scientific notation to find the distance between Earth and the star in miles. Write the answer in scientific notation.

Debt At the end of fiscal year 2015 the gross United States federal government debt was estimated to be approximately $18,600,000,000,000 ($18.6 trillion), according to the Federal Budget. The population of the United States was approximately 300,000,000 people at the end of fiscal year 2015.

ⓐ Write the debt in scientific notation.
ⓑ Write the population in scientific notation.
ⓒ Find the amount of debt per person by using scientific notation to divide the debt by the population. Write the answer in scientific notation.

ⓐ $1.86 \times 10^{13}$ ⓑ $3 \times 10^{8}$ ⓒ $6.2 \times 10^{4}$

Writing Exercises

ⓐ Explain the meaning of the exponent in the expression $2 cubed$ .
ⓑ Explain the meaning of the exponent in the expression $2 to the power −3$ .

When you convert a number from decimal notation to scientific notation, how do you know if the exponent will be positive or negative?

answers will vary

Self Check

ⓐ After completing the exercises, use this checklist to evaluate your mastery of the objectives of this section.

This is a table that has six rows and four columns. In the first row, which is a header row, the cells read from left to right “I can…,” “Confidently,” “With some help,” and “No-I don’t get it!” The first column below “I can…” reads “use the definition of a negative exponent,” “simplify expressions with integer exponents,” “convert from decimal notation to scientific notation,” “convert scientific notation to decimal form,” and “multiply and divide using scientific notation.” The rest of the cells are blank.

ⓑ Overall, after looking at the checklist, do you think you are well-prepared for the next section? Why or why not?

Chapter 6 Review Exercises

Add and Subtract Polynomials

Identify Polynomials, Monomials, Binomials and Trinomials

In the following exercises, determine if each of the following polynomials is a monomial, binomial, trinomial, or other polynomial.

ⓐ $11 c^{4} - 23 c^{2} + 1$
ⓑ $9 p^{3} + 6 p^{2} - p - 5$
ⓒ $\frac{3}{7} x + \frac{5}{14}$
ⓓ 10
ⓔ $2 y minus 12$

ⓐ $a^{2} - b^{2}$
ⓑ $24 d cubed$
ⓒ $x^{2} + 8 x - 10$
ⓓ $m^{2} n^{2} - 2 m n + 6$
ⓔ $7 y^{3} + y^{2} - 2 y - 4$

ⓐ binomial ⓑ monomial ⓒ trinomial ⓓ trinomial ⓔ other polynomial

Determine the Degree of Polynomials

In the following exercises, determine the degree of each polynomial.

ⓐ $3 x^{2} + 9 x + 10$
ⓑ $14 a squared b c$
ⓒ $6 y plus 1$
ⓓ $n^{3} - 4 n^{2} + 2 n - 8$
ⓔ $−19$

ⓐ $5 p^{3} - 8 p^{2} + 10 p - 4$
ⓑ $−20 q to the power 4$
ⓒ $x^{2} + 6 x + 12$
ⓓ $23 r^{2} s^{2} - 4 r s + 5$
ⓔ 100

ⓐ 3 ⓑ 4 ⓒ 2 ⓓ 4 ⓔ 0

Add and Subtract Monomials

In the following exercises, add or subtract the monomials.

$5y cubed plus 8 y cubed$

$−14 k plus 19 k$

$5 k$

$12 q minus open parenthesis −6 q close parenthesis$

$−9 c minus 18 c$

$−27 c$

$12x - 4 y - 9 x$

$3 m^{2} + 7 n^{2} - 3 m^{2}$

$7 n squared$

$6 x^{2} y - 4 x + 8 x y^{2}$

$13a plus b$

Add and Subtract Polynomials

In the following exercises, add or subtract the polynomials.

$(5 x^{2} + 12 x + 1) + (6 x^{2} - 8 x + 3)$

$(9 p^{2} - 5 p + 3) + (4 p^{2} - 4)$

$13 p^{2} - 5 p - 1$

$(10 m^{2} - 8 m - 1) - (5 m^{2} + m - 2)$

$(7 y^{2} - 8 y) - (y - 4)$

$7 y^{2} - 9 y + 4$

Subtract
$(3 s^{2} + 10) from (15 s^{2} - 2 s + 8)$

Find the sum of $(a^{2} + 6 a + 9) and (5 a^{3} - 7)$

$5 a^{3} + a^{2} + 6 a + 2$

Evaluate a Polynomial for a Given Value of the Variable

In the following exercises, evaluate each polynomial for the given value.

Evaluate $3 y^{2} - y + 1$ when:

ⓐ $y equals 5$
ⓑ $y equals −1$
ⓒ $y equals 0$

Evaluate $10 minus 12 x$ when:

ⓐ $x equals 3$
ⓑ $x equals 0$
ⓒ $x equals −1$

ⓐ $−26$ ⓑ 10 ⓒ 22

Randee drops a stone off the 200 foot high cliff into the ocean. The polynomial $−16 t squared plus 200$ gives the height of a stone $t$ seconds after it is dropped from the cliff. Find the height after $t equals 3$ seconds.

A manufacturer of stereo sound speakers has found that the revenue received from selling the speakers at a cost of p dollars each is given by the polynomial $−4 p squared plus 460 p.$ Find the revenue received when $p equals 75$ dollars.

12,000

Use Multiplication Properties of Exponents

Simplify Expressions with Exponents

In the following exercises, simplify.

$10 to the power 4$

$17 to the power 1$

${(\frac{2}{9})}^{2}$

$open parenthesis 0.5 close parenthesis cubed$

0.125

$open parenthesis −2 close parenthesis to the power 6$

$− 2 to the power 6$

$−64$

Simplify Expressions Using the Product Property for Exponents

In the following exercises, simplify each expression.

$x^{4} \cdot x^{3}$

$p^{15} \cdot p^{16}$

$p to the power 31$

$4^{10} \cdot 4^{6}$

$8 \cdot 8^{5}$

$8 to the power 6$

$n \cdot n^{2} \cdot n^{4}$

$y^{c} \cdot y^{3}$

$y^{c + 3}$

Simplify Expressions Using the Power Property for Exponents

In the following exercises, simplify each expression.

$open parenthesis m cubed close parenthesis to the power 5$

$open parenthesis 5 cubed close parenthesis squared$

$5 to the power 6$

${(y^{4})}^{x}$

${(3^{r})}^{s}$

$3 to the power r s$

Simplify Expressions Using the Product to a Power Property

In the following exercises, simplify each expression.

$open parenthesis 4 a close parenthesis squared$

$open parenthesis −5 y close parenthesis cubed$

$−125 y cubed$

$open parenthesis 2 m n close parenthesis to the power 5$

$open parenthesis 10 x y z close parenthesis cubed$

$1000 x cubed y cubed z cubed$

Simplify Expressions by Applying Several Properties

In the following exercises, simplify each expression.

${(p^{2})}^{5} \cdot {(p^{3})}^{6}$

$open parenthesis 4 a cubed b squared close parenthesis cubed$

$64 a^{9} b^{6}$

$open parenthesis 5 x close parenthesis squared open parenthesis 7 x close parenthesis$

$open parenthesis 2 q cubed close parenthesis to the power 4 open parenthesis 3 q close parenthesis squared$

$144 q to the power 14$

${(\frac{1}{3} x^{2})}^{2} {(\frac{1}{2} x)}^{3}$

${(\frac{2}{5} m^{2} n)}^{3}$

$\frac{8}{125} m^{6} n^{3}$

Multiply Monomials

In the following exercises 8, multiply the monomials.

$open parenthesis −15 x squared close parenthesis open parenthesis 6 x to the power 4 close parenthesis$

$open parenthesis −9 n to the power 7 close parenthesis open parenthesis −16 n close parenthesis$

$144 n to the power 8$

$(7 p^{5} q^{3}) (8 p q^{9})$

$(\frac{5}{9} a b^{2}) (27 a b^{3})$

$15 a squared b to the power 5$

Multiply Polynomials

Multiply a Polynomial by a Monomial

In the following exercises, multiply.

$7 open parenthesis a plus 9 close parenthesis$

$−4 open parenthesis y plus 13 close parenthesis$

$−4 y minus 52$

$−5 open parenthesis r minus 2 close parenthesis$

$p open parenthesis p plus 3 close parenthesis$

$p squared plus 3 p$

$− m open parenthesis m plus 15 close parenthesis$

$−6 u open parenthesis 2 u plus 7 close parenthesis$

$−12 u squared minus 42 u$

$9 (b^{2} + 6 b + 8)$

$3 q^{2} (q^{2} - 7 q + 6)$ 3

$9 q^{4} - 63 q^{3} + 54 q^{2}$

$open parenthesis 5 z minus 1 close parenthesis z$

$(b - 4) \cdot 11$

$11 b minus 44$

Multiply a Binomial by a Binomial

In the following exercises, multiply the binomials using: ⓐ the Distributive Property, ⓑ the FOIL method, ⓒ the Vertical Method.

$(x - 4) (x + 10)$

$(6 y - 7) (2 y - 5)$

ⓐ $12 y^{2} - 44 y + 35$ ⓑ $12 y^{2} - 44 y + 35$ ⓒ $12 y^{2} - 44 y + 35$

In the following exercises, multiply the binomials. Use any method.

$(x + 3) (x + 9)$

$(y - 4) (y - 8)$

$y^{2} - 12 y + 32$

$(p - 7) (p + 4)$

$(q + 16) (q - 3)$

$q^{2} + 13 q - 48$

$(5 m - 8) (12 m + 1)$

$(u^{2} + 6) (u^{2} - 5)$

$u^{4} + u^{2} - 30$

$(9 x - y) (6 x - 5)$

$(8 m n + 3) (2 m n - 1)$

$16 m^{2} n^{2} - 2 m n - 3$

Multiply a Trinomial by a Binomial

In the following exercises, multiply using ⓐ the Distributive Property, ⓑ the Vertical Method.

$(n + 1) (n^{2} + 5 n - 2)$

$(3 x - 4) (6 x^{2} + x - 10)$

ⓐ $18 x^{3} - 21 x^{2} - 34 x + 40$ ⓑ $18 x^{3} - 21 x^{2} - 34 x + 40$

In the following exercises, multiply. Use either method.

$(y - 2) (y^{2} - 8 y + 9)$

$(7 m + 1) (m^{2} - 10 m - 3)$

$7 m^{3} - 69 m^{2} - 31 m - 3$

Special Products

Square a Binomial Using the Binomial Squares Pattern

In the following exercises, square each binomial using the Binomial Squares Pattern.

$open parenthesis c plus 11 close parenthesis squared$

$open parenthesis q minus 15 close parenthesis squared$

$q^{2} - 30 q + 225$

${(x + \frac{1}{3})}^{2}$

$open parenthesis 8 u plus 1 close parenthesis squared$

$64 u^{2} + 16 u + 1$

$open parenthesis 3 n cubed minus 2 close parenthesis squared$

$open parenthesis 4 a minus 3 b close parenthesis squared$

$16 a^{2} - 24 a b + 9 b^{2}$

Multiply Conjugates Using the Product of Conjugates Pattern

In the following exercises, multiply each pair of conjugates using the Product of Conjugates Pattern.

$(s - 7) (s + 7)$

$(y + \frac{2}{5}) (y - \frac{2}{5})$

$y^{2} - \frac{4}{25}$

$(12 c + 13) (12 c - 13)$

$(6 - r) (6 + r)$

$36 minus r squared$

$(u + \frac{3}{4} v) (u - \frac{3}{4} v)$

$(5 p^{4} - 4 q^{3}) (5 p^{4} + 4 q^{3})$

$25 p^{8} - 16 q^{6}$

Recognize and Use the Appropriate Special Product Pattern

In the following exercises, find each product.

$open parenthesis 3 m plus 10 close parenthesis squared$

$(6 a + 11) (6 a - 11)$

$36 a squared minus 121$

$(5 x + y) (x - 5 y)$

${(c^{4} + 9 d)}^{2}$

$c^{8} + 18 c^{4} d + 81 d^{2}$

$(p^{5} + q^{5}) (p^{5} - q^{5})$

$(a^{2} + 4 b) (4 a - b^{2})$

$4 a^{3} - a^{2} b^{2} + 16 a b - 4 b^{3}$

Divide Monomials

Simplify Expressions Using the Quotient Property for Exponents

In the following exercises, simplify.

$\frac{u^{24}}{u^{6}}$

$\frac{10^{25}}{10^{5}}$

$10 to the power 20$

$\frac{3^{4}}{3^{6}}$

$\frac{v^{12}}{v^{48}}$

$\frac{1}{v^{36}}$

$\frac{x}{x^{5}}$

$\frac{5}{5^{8}}$

$\frac{1}{5^{7}}$

Simplify Expressions with Zero Exponents

In the following exercises, simplify.

$75 to the power 0$

$x to the power 0$

$− 12 to the power 0$

$open parenthesis − 12 to the power 0 close parenthesis$ $open parenthesis −12 close parenthesis to the power 0$

−1

$25 x to the power 0$

$open parenthesis 25 x close parenthesis to the power 0$

$19 n^{0} - 25 m^{0}$

${(19 n)}^{0} - {(25 m)}^{0}$

Simplify Expressions Using the Quotient to a Power Property

In the following exercises, simplify.

${(\frac{2}{5})}^{3}$

${(\frac{m}{3})}^{4}$

$\frac{m^{4}}{81}$

${(\frac{r}{s})}^{8}$

${(\frac{x}{2 y})}^{6}$

$\frac{x^{6}}{64 y^{6}}$

Simplify Expressions by Applying Several Properties

In the following exercises, simplify.

$\frac{{(x^{3})}^{5}}{x^{9}}$

$\frac{n^{10}}{{(n^{5})}^{2}}$

${(\frac{q^{6}}{q^{8}})}^{3}$

${(\frac{r^{8}}{r^{3}})}^{4}$

$r to the power 20$

${(\frac{c^{2}}{d^{5}})}^{9}$

${(\frac{3 x^{4}}{2 y^{2}})}^{5}$

$\frac{243 x^{20}}{32 y^{10}}$

${(\frac{v^{3} v^{9}}{v^{6}})}^{4}$

$\frac{{(3 n^{2})}^{4} {(−5 n^{4})}^{3}}{{(−2 n^{5})}^{2}}$

$- \frac{10,125 n^{10}}{4}$

Divide Monomials

In the following exercises, divide the monomials.

$−65 y^{14} \div 5 y^{2}$

$\frac{64 a^{5} b^{9}}{−16 a^{10} b^{3}}$

$- \frac{4 b^{6}}{a^{5}}$

$\frac{144 x^{15} y^{8} z^{3}}{18 x^{10} y^{2} z^{12}}$

$\frac{(8 p^{6} q^{2}) (9 p^{3} q^{5})}{16 p^{8} q^{7}}$

$\frac{9 p}{2}$

Divide Polynomials

Divide a Polynomial by a Monomial

In the following exercises, divide each polynomial by the monomial.

$\frac{42 z^{2} - 18 z}{6}$

$(35 x^{2} - 75 x) \div 5 x$

$7 x minus 15$

$\frac{81 n^{4} + 105 n^{2}}{−3}$

$\frac{550 p^{6} - 300 p^{4}}{10 p^{3}}$

$55 p cubed minus 30 p$

$(63 x y^{3} + 56 x^{2} y^{4}) \div (7 x y)$

$\frac{96 a^{5} b^{2} - 48 a^{4} b^{3} - 56 a^{2} b^{4}}{8 a b^{2}}$

$12 a^{4} - 6 a^{3} b - 7 a b^{2}$

$\frac{57 m^{2} - 12 m + 1}{−3 m}$

$\frac{105 y^{5} + 50 y^{3} - 5 y}{5 y^{3}}$

$21 y^{2} + 10 - \frac{1}{y^{2}}$

Divide a Polynomial by a Binomial

In the following exercises, divide each polynomial by the binomial.

$(k^{2} - 2 k - 99) \div (k + 9)$

$(v^{2} - 16 v + 64) \div (v - 8)$

$v minus 8$

$(3 x^{2} - 8 x - 35) \div (x - 5)$

$(n^{2} - 3 n - 14) \div (n + 3)$

$n - 6 + \frac{4}{n + 3}$

$(4 m^{3} + m - 5) \div (m - 1)$

$(u^{3} - 8) \div (u - 2)$

$u^{2} + 2 u + 4$

Integer Exponents and Scientific Notation

Use the Definition of a Negative Exponent

In the following exercises, simplify.

$9 to the power −2$

$open parenthesis −5 close parenthesis to the power −3$

$- \frac{1}{125}$

$3 \cdot 4^{−3}$

$open parenthesis 6 u close parenthesis to the power −3$

$\frac{1}{216 u^{3}}$

${(\frac{2}{5})}^{−1}$

${(\frac{3}{4})}^{−2}$

$\frac{16}{9}$

Simplify Expressions with Integer Exponents

In the following exercises, simplify.

$p^{−2} \cdot p^{8}$

$q^{−6} \cdot q^{−5}$

$\frac{1}{q^{11}}$

$(c^{−2} d) (c^{−3} d^{−2})$

${(y^{8})}^{−1}$

$\frac{1}{y^{8}}$

${(q^{−4})}^{−3}$

$\frac{a^{8}}{a^{12}}$

$\frac{1}{a^{4}}$

$\frac{n^{5}}{n^{−4}}$

$\frac{r^{−2}}{r^{−3}}$

$r$

Convert from Decimal Notation to Scientific Notation

In the following exercises, write each number in scientific notation.

8,500,000

0.00429

$4.29 \times 10^{−3}$

The thickness of a dime is about 0.053 inches.

In 2015, the population of the world was about 7,200,000,000 people.

$7.2 \times 10^{9}$

Convert Scientific Notation to Decimal Form

In the following exercises, convert each number to decimal form.

$3.8 \times 10^{5}$

$1.5 \times 10^{10}$

$15,000,000,000$

$9.1 \times 10^{−7}$

$5.5 \times 10^{−1}$

$0.55$

Multiply and Divide Using Scientific Notation

In the following exercises, multiply and write your answer in decimal form.

$(2 \times 10^{5}) (4 \times 10^{−3})$

$(3.5 \times 10^{−2}) (6.2 \times 10^{−1})$

$0.0217$

In the following exercises, divide and write your answer in decimal form.

$\frac{8 \times 10^{5}}{4 \times 10^{−1}}$

$\frac{9 \times 10^{−5}}{3 \times 10^{2}}$

$0.0000003$

Chapter Practice Test

For the polynomial $10 x^{4} + 9 y^{2} - 1$
ⓐ Is it a monomial, binomial, or trinomial?
ⓑ What is its degree?

In the following exercises, simplify each expression.

$(12 a^{2} - 7 a + 4) + (3 a^{2} + 8 a - 10)$

$15 a^{2} + a - 6$

$(9 p^{2} - 5 p + 1) - (2 p^{2} - 6)$

${(- \frac{2}{5})}^{3}$

$- \frac{8}{125}$

$u \cdot u^{4}$

$open parenthesis 4 a cubed b to the power 5 close parenthesis squared$

$16 a^{6} b^{10}$

$(−9 r^{4} s^{5}) (4 r s^{7})$

$3 k (k^{2} - 7 k + 13)$

$3 k^{3} - 21 k^{2} + 39 k$

$(m + 6) (m + 12)$

$(v - 9) (9 v - 5)$

$9 v^{2} - 86 v + 45$

$(4 c - 11) (3 c - 8)$

$(n - 6) (n^{2} - 5 n + 4)$

$n^{3} - 11 n^{2} + 34 n - 24$

$(2 x - 15 y) (5 x + 7 y)$

$(7 p - 5) (7 p + 5)$

$49 p squared minus 25$

$open parenthesis 9 v minus 2 close parenthesis squared$

$\frac{3^{8}}{3^{10}}$

$\frac{1}{9}$

${(\frac{m^{4} \cdot m}{m^{3}})}^{6}$

${(87 x^{15} y^{3} z^{22})}^{0}$

$1$

$\frac{80 c^{8} d^{2}}{16 c d^{10}}$

$\frac{12 x^{2} + 42 x - 6}{2 x}$

$6 x + 21 - \frac{3}{x}$

$(70 x y^{4} + 95 x^{3} y) \div 5 x y$

$\frac{64 x^{3} - 1}{4 x - 1}$

$16 x^{2} + 4 x + 1$

$(y^{2} - 5 y - 18) \div (y + 3)$

$5 to the power −2$

$\frac{1}{25}$

$open parenthesis 4 m close parenthesis to the power −3$

$q^{−4} \cdot q^{−5}$

$\frac{1}{q^{9}}$

$\frac{n^{−2}}{n^{−10}}$

Convert 83,000,000 to scientific notation.

$8.3 \times 10^{7}$

Convert $6.91 \times 10^{−5}$ to decimal form.

In the following exercises, simplify, and write your answer in decimal form.

$(3.4 \times 10^{9}) (2.2 \times 10^{−5})$

74,800

$\frac{8.4 \times 10^{−3}}{4 \times 10^{3}}$

A helicopter flying at an altitude of 1000 feet drops a rescue package. The polynomial $−16 t squared plus 1000$ gives the height of the package $t$ seconds a after it was dropped. Find the height when $t equals 6$ seconds.

424 feet

	$\frac{r^{5}}{r^{−4}}$
Use the Quotient Property, $\frac{a^{m}}{a^{n}} = a^{m - n} .$	$r^{5 - (−4)}$
Simplify.	$r to the power 9$

ⓐ	$4 to the power −2$
Use the definition of a negative exponent, $a^{− n} = \frac{1}{a^{n}}$ .	$\frac{1}{4^{2}}$
Simplify.	$\frac{1}{16}$
ⓑ	$10 to the power −3$
Use the definition of a negative exponent, $a^{− n} = \frac{1}{a^{n}}$ .	$\frac{1}{10^{3}}$
Simplify.	$\frac{1}{1000}$

ⓐ	$\frac{1}{y^{−4}}$
Use the property of a negative exponent, $\frac{1}{a^{− n}} = a^{n}$ .	$y to the power 4$
ⓑ	$\frac{1}{3^{−2}}$
Use the property of a negative exponent, $\frac{1}{a^{− n}} = a^{n}$ .	$3 squared$
Simplify.	$9$