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📚 Intermediate Algebra 2e
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8.2 Simplify Radical Expressions

Use the Product Property to Simplify Radical Expressions

We will simplify radical expressions in a way similar to how we simplified fractions. A fraction is simplified if there are no common factors in the numerator and denominator. To simplify a fraction, we look for any common factors in the numerator and denominator.

A radical expression, an, is considered simplified if it has no factors of mn. So, to simplify a radical expression, we look for any factors in the radicand that are powers of the index.

For example, 5 is considered simplified because there are no perfect square factors in 5. But 12 is not simplified because 12 has a perfect square factor of 4.

Similarly, 43 is simplified because there are no perfect cube factors in 4. But 243 is not simplified because 24 has a perfect cube factor of 8.

To simplify radical expressions, we will also use some properties of roots. The properties we will use to simplify radical expressions are similar to the properties of exponents. We know that (ab)n=anbn. The corresponding of Product Property of Roots says that abn=an·bn.

We use the Product Property of Roots to remove all perfect square factors from a square root.

Notice in the previous example that the simplified form of 98 is 72, which is the product of an integer and a square root. We always write the integer in front of the square root.

Be careful to write your integer so that it is not confused with the index. The expression 72 is very different from 27.

We will apply this method in the next example. It may be helpful to have a table of perfect squares, cubes, and fourth powers.

The next example is much like the previous examples, but with variables. Don’t forget to use the absolute value signs when taking an even root of an expression with a variable in the radical.

We follow the same procedure when there is a coefficient in the radicand. In the next example, both the constant and the variable have perfect square factors.

In the next example, we continue to use the same methods even though there are more than one variable under the radical.

We have seen how to use the order of operations to simplify some expressions with radicals. In the next example, we have the sum of an integer and a square root. We simplify the square root but cannot add the resulting expression to the integer since one term contains a radical and the other does not. The next example also includes a fraction with a radical in the numerator. Remember that in order to simplify a fraction you need a common factor in the numerator and denominator.

Use the Quotient Property to Simplify Radical Expressions

Whenever you have to simplify a radical expression, the first step you should take is to determine whether the radicand is a perfect power of the index. If not, check the numerator and denominator for any common factors, and remove them. You may find a fraction in which both the numerator and the denominator are perfect powers of the index.

In the last example, our first step was to simplify the fraction under the radical by removing common factors. In the next example we will use the Quotient Property to simplify under the radical. We divide the like bases by subtracting their exponents,

aman=amn,a0

Remember the Quotient to a Power Property? It said we could raise a fraction to a power by raising the numerator and denominator to the power separately.

(ab)m=ambm,b0

We can use a similar property to simplify a root of a fraction. After removing all common factors from the numerator and denominator, if the fraction is not a perfect power of the index, we simplify the numerator and denominator separately.

Be sure to simplify the fraction in the radicand first, if possible.

In the next example, there is nothing to simplify in the denominators. Since the index on the radicals is the same, we can use the Quotient Property again, to combine them into one radical. We will then look to see if we can simplify the expression.

Key Concepts

  • Simplified Radical Expression
    • For real numbers a, m and n2
      an is considered simplified if a has no factors of mn
  • Product Property of nth Roots
    • For any real numbers, an and bn, and for any integer n2
      abn=an·bn and an·bn=abn
  • How to simplify a radical expression using the Product Property
    1. Find the largest factor in the radicand that is a perfect power of the index.
      Rewrite the radicand as a product of two factors, using that factor.
    2. Use the product rule to rewrite the radical as the product of two radicals.
    3. Simplify the root of the perfect power.
  • Quotient Property of Radical Expressions
    • If an and bn are real numbers, b0, and for any integer n2 then,
      abn=anbn and anbn=abn
  • How to simplify a radical expression using the Quotient Property.
    1. Simplify the fraction in the radicand, if possible.
    2. Use the Quotient Property to rewrite the radical as the quotient of two radicals.
    3. Simplify the radicals in the numerator and the denominator.

Practice Makes Perfect

Use the Product Property to Simplify Radical Expressions

In the following exercises, use the Product Property to simplify radical expressions.

27

33

80

125

55

96

147

73

450

800

202

675

324645

224225

62531286

6442563

244443

31254813

In the following exercises, simplify using absolute value signs as needed.

y11r53s104

| y5 |yrr23s2s24

m13u75v116

n21q83n108

n10nq2q23
|n|n28

r25p85m54

125r13108x5348y64

5r65r3x4x23
2|y|3y24

80s1596a75128b76

242m23405m104160n85

11|m11|2m3m25m242n5n35

175n13512p55324q74

147m7n1148x6y7332x5y44

7|m3n5|3mn2x2y26y32|xy|2x4

96r3s380x7y6380x8y94

192q3r754m9n10381a9b84

8|qr3|3qr3m3n32n33a2b2a4

150m9n381p7q83162c11d124

−8643−2564

−643 ⓑ not real

−4865−646

−325−18

−2 ⓑ not real

−83−164

5+1210242

5+2356

8+968804

1+453+903

1+351+10

3+12515+755

Use the Quotient Property to Simplify Radical Expressions

In the following exercises, use the Quotient Property to simplify square roots.

458082731814

342313

7298248136964

1003681375312564

533514

12116162503321624

x10x6p11p23q17q134

x2p3|q|

p20p10d12d75m12m48

y4y8u21u115v30v126

1y2u2|v3|

q8q14r14r53c21c94

96x7121

4|x3|6x11

108y449

300m564

5m23m4

125n7169

98r5100

7r22r10

180s10144

28q6225

2|q3|715

150r3256

75r9s854a8b3364c5d44

5r43rs43a22a23b
2|c|4c4|d|

72x5y696r11s55128u7v126

28p7q281s8t3364p15q124

2|p3|7p|q|3s23s23t
2|p3|4p34|q3|

45r3s10625u10v33729c21d84

32x5y318x3y5x6y940x5y335a8b680a3b24

4|xy|3y2x32|ab|a42

75r6s848rs424x8y481x2y332m9n2162mn24

27p2q108p4q316c5d7250c2d232m9n7128m3n6

12|pq|2cdd235
|mn|2

50r5s2128r2s624m9n7375m4n381m2n8256m1n24

45p95q264424128x852x25

3p4p|q|224
2x2x5

80q55q−62535380m745m4

50m72m125023486y92y34

5|m3|553
3|y|3y24

72n112n16263160r105r34

Writing Exercises

Explain why x4=x2. Then explain why x16=x8.

Answers will vary.

Explain why 7+9 is not equal to 7+9.

Explain how you know that x105=x2.

Answers will vary.

Explain why −644 is not a real number but −643 is.

Self Check

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

This table has 3 rows and 4 columns. The first row is a header row and it labels each column. The first column header is “I can…”, the second is “Confidently”, the third is “With some help”, and the fourth is “No, I don’t get it”. Under the first column are the phrases “use the product property to simplify radical expressions” and “use the quotient property to simplify radical expressions”. The other columns are left blank so that the learner may indicate their mastery level for each topic.

ⓑ After reviewing this checklist, what will you do to become confident for all objectives?