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📚 Prealgebra 2e
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10.4 Divide Monomials

Simplify Expressions Using the Quotient Property of Exponents

Earlier in this chapter, we developed the properties of exponents for multiplication. We summarize these properties here.

Now we will look at the exponent properties for division. A quick memory refresher may help before we get started. In Fractions you learned that fractions may be simplified by dividing out common factors from the numerator and denominator using the Equivalent Fractions Property. This property will also help us work with algebraic fractions—which are also quotients.

As before, we'll try to discover a property by looking at some examples.

Considerx5x2andx2x3What do they mean?xxxxxxxxxxxxUse the Equivalent Fractions Property.xxxxxxx1xx1xxxSimplify.x31x

Notice that in each case the bases were the same and we subtracted the exponents.

  • When the larger exponent was in the numerator, we were left with factors in the numerator and 1 in the denominator, which we simplified.
  • When the larger exponent was in the denominator, we were left with factors in the denominator, and 1 in the numerator, which could not be simplified.

We write:

x5x2x2x3x521x32x31x

A couple of examples with numbers may help to verify this property.

3432=?3425253=?1532819=?3225125=?1519=915=15

When we work with numbers and the exponent is less than or equal to 3, we will apply the exponent. When the exponent is greater than 3, we leave the answer in exponential form.

Simplify Expressions with Zero Exponents

A special case of the Quotient Property is when the exponents of the numerator and denominator are equal, such as an expression like amam. From earlier work with fractions, we know that

22=11717=1−43−43=1

In words, a number divided by itself is 1. So xx=1, for any x (x0), since any number divided by itself is 1.

The Quotient Property of Exponents shows us how to simplify aman when m>n and when n<m by subtracting exponents. What if m=n?

Now we will simplify amam in two ways to lead us to the definition of the zero exponent.

Consider first 88, which we know is 1.

88=1
Write 8 as 23.2323=1
Subtract exponents.233=1
Simplify.20=1
This image demonstrates the proof that any non-zero number raised to the power of zero equals one (a^0 = 1), using both exponent rules and the cancellation of factors.

We see aman simplifies to a a0 and to 1. So a0=1.

In this text, we assume any variable that we raise to the zero power is not zero.

Now that we have defined the zero exponent, we can expand all the Properties of Exponents to include whole number exponents.

What about raising an expression to the zero power? Let's look at (2x)0. We can use the product to a power rule to rewrite this expression.

(2x)0
Use the Product to a Power Rule.20x0
Use the Zero Exponent Property.11
Simplify.1

This tells us that any non-zero expression raised to the zero power is one.

Simplify Expressions Using the Quotient to a Power Property

Now we will look at an example that will lead us to the Quotient to a Power Property.

(xy)3
This meansxyxyxy
Multiply the fractions.xxxyyy
Write with exponents.x3y3

Notice that the exponent applies to both the numerator and the denominator.

We see that (xy)3 is x3y3.

We write:(xy)3x3y3

This leads to the Quotient to a Power Property for Exponents.

An example with numbers may help you understand this property:

(23)3=?2333232323=?827827=827

Simplify Expressions by Applying Several Properties

We'll now summarize all the properties of exponents so they are all together to refer to as we simplify expressions using several properties. Notice that they are now defined for whole number exponents.

Divide Monomials

We have now seen all the properties of exponents. We'll use them to divide monomials. Later, you'll use them to divide polynomials.

When we divide monomials with more than one variable, we write one fraction for each variable.

Once you become familiar with the process and have practiced it step by step several times, you may be able to simplify a fraction in one step.

In all examples so far, there was no work to do in the numerator or denominator before simplifying the fraction. In the next example, we'll first find the product of two monomials in the numerator before we simplify the fraction.

Key Concepts

  • Equivalent Fractions Property
    • If a,b,c are whole numbers where b0,c0, then

      ab=a·cb·canda·cb·c=ab

  • Zero Exponent
    • If a is a non-zero number, then a0=1.
    • Any nonzero number raised to the zero power is 1.
  • Quotient Property for Exponents
    • If a is a real number, a0, and m,n are whole numbers, then

      aman=amn,m>nandaman=1anm,n>m

  • Quotient to a Power Property for Exponents
    • If a and b are real numbers, b0, and m is a counting number, then

      (ab)m=ambm

    • To raise a fraction to a power, raise the numerator and denominator to that power.

Practice Makes Perfect

Simplify Expressions Using the Quotient Property of Exponents

In the following exercises, simplify.

4842

46

31234

x12x3

x9

u9u3

r5r

r4

y4y

y4y20

1y16

x10x30

1031015

11012

r2r8

aa9

1a8

225

Simplify Expressions with Zero Exponents

In the following exercises, simplify.

50

1

100

a0

1

x0

70

−1

40

  1. (10p)0
  2. 10p0
  1. ⓐ 1
  2. ⓑ 10
  1. (3a)0
  2. 3a0
  1. (−27x5y)0
  2. −27x5y0
  1. ⓐ 1
  2. ⓑ −27x5
  1. (−92y8z)0
  2. −92y8z0
  1. 150
  2. 151
  1. ⓐ 1
  2. ⓑ 15
  1. 60
  2. 61

2·x0+5·y0

7

8·m04·n0

Simplify Expressions Using the Quotient to a Power Property

In the following exercises, simplify.

(32)5

24332

(45)3

(m6)3

m3216

(p2)5

(xy)10

x10y10

(ab)8

(a3b)2

a29b2

(2xy)4

Simplify Expressions by Applying Several Properties

In the following exercises, simplify.

(x2)4x5

x3

(y4)3y7

(u3)4u10

u2

(y2)5y6

y8(y5)2

1y2

p11(p5)3

r5r4·r

1

a3·a4a7

(x2x8)3

1x18

(uu10)2

(a4·a6a3)2

a14

(x3·x8x4)3

(y3)5(y4)3

y3

(z6)2(z2)4

(x3)6(x4)7

1x10

(x4)8(x5)7

(2r35s)4

16r12625s4

(3m24n)3

(3y2·y5y15·y8)0

1

(15z4·z90.3z2)0

(r2)5(r4)2(r3)7

1r3

(p4)2(p3)5(p2)9

(3x4)3(2x3)2(6x5)2

3x8

(−2y3)4(3y4)2(−6y3)2

Divide Monomials

In the following exercises, divide the monomials.

48b8÷6b2

8b6

42a14÷6a2

36x3÷(−2x9)

−18x6

20u8÷(−4u6)

18x39x2

2x

36y94y7

−35x7−42x13

56x6

18x5−27x9

18r5s3r3s9

6r2s8

24p7q6p2q5

8mn1064mn4

n68

10a4b50a2b6

−12x4y915x6y3

4y65x2

48x11y9z336x6y8z5

64x5y9z748x7y12z6

4z3x2y3

(10u2v)(4u3v6)5u9v2

(6m2n)(5m4n3)3m10n2

10n2m4

(6a4b3)(4ab5)(12a8b)(a3b)

(4u5v4)(15u8v)(12u3v)(u6v)

5u4v3

Mixed Practice

  1. 24a5+2a5
  2. 24a52a5
  3. 24a52a5
  4. 24a5÷2a5
  1. 15n10+3n10
  2. 15n103n10
  3. 15n103n10
  4. 15n10÷3n10
  1. 18n10
  2. 12n10
  3. 45n20
  4. 5
  1. p4p6
  2. (p4)6
  1. q5q3
  2. (q5)3
  1. q8
  2. q15
  1. y3y
  2. yy3
  1. z6z5
  2. z5z6
  1. z
  2. 1z

(8x5)(9x)÷6x3

(4y)(12y7)÷8y2

6y6

27a73a3+54a99a5

32c114c5+42c96c3

15c6

32y58y260y105y7

48x66x435x97x7

3x2

63r6s39r4s272r2s26s

56y4z57y3z345y2z25y

yz2

Everyday Math

Memory One megabyte is approximately 106 bytes. One gigabyte is approximately 109 bytes. How many megabytes are in one gigabyte?

Memory One megabyte is approximately 106 bytes. One terabyte is approximately 1012 bytes. How many megabytes are in one terabyte?

1,000,000

Writing Exercises

Vic thinks the quotient x20x4 simplifies to x5. What is wrong with his reasoning?

Mai simplifies the quotient y3y by writing y3y=3. What is wrong with her reasoning?

Answers will vary.

When Dimple simplified 30 and (−3)0 she got the same answer. Explain how using the Order of Operations correctly gives different answers.

Roxie thinks n0 simplifies to 0. What would you say to convince Roxie she is wrong?

Answers will vary.

Self Check

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

A math self-assessment sheet listing various exponent properties and monomial division skills, with columns for students to rate their proficiency: Confidently, With some help, or No-I don't get it!.
Figure 10.6

ⓑ On a scale of 1–10, how would you rate your mastery of this section in light of your responses on the checklist? How can you improve this?