Simplify Radical Expressions

By the end of this section, you will be able to:

Before you get started, take this readiness quiz.

  1. Simplify: x9x4.

    If you missed this problem, review [link].

  2. Simplify: y3y11.

    If you missed this problem, review [link].

  3. Simplify: (n2)6.

    If you missed this problem, review [link].

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.

Simplified Radical Expression

For real numbers a and m, and n2,

anis considered simplified ifahas no factors ofmn

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.

Product Property of *n*th Roots

If an

and bn

are real numbers, and n2

is an integer, then

abn=an·bnandan·bn=abn

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

Simplify Square Roots Using the Product Property of Roots

Simplify: 98.

![The first step in the process is to find the largest factor in the radicand that is a perfect power of the index and rewrite the radicand as a product of two factors, using that factor. We see that 49 is the largest factor of 98 that has a power of 2. In other words 49 is the largest perfect square factor of 98. We can write 98 equals 49 times 2. Always write the perfect square factor first. The square root of 98 can then be written as the square root of the quantity 49 times 2 in parentheses.](/algebra-intermediate-book/resources/CNX_IntAlg_Figure_08_02_001a_img.jpg) ![The second step in the process is to use the product rule to rewrite the radical as the product of two radicals. The square root of the quantity 49 times 2 in parentheses can be written as the square root of 49 times the square root of 2.](/algebra-intermediate-book/resources/CNX_IntAlg_Figure_08_02_001b_img.jpg) ![The third step is to simplify the root of the perfect power. The square root of 49 times the square root of 2 can be written as 7 times the square root of 2.](/algebra-intermediate-book/resources/CNX_IntAlg_Figure_08_02_001c_img.jpg)

Simplify: 48.

43

Simplify: 45.

35

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.

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.

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

Simplify: 500

163

2434.

* * *

500Rewrite the radicand as a productusing the largest perfect square factor.100·5Rewrite the radical as the product of tworadicals100·5Simplify.105

* * *

163Rewrite the radicand as a product usingthe greatest perfect cube factor.23=88·23Rewrite the radical as the product of tworadicals.83·23Simplify.223

* * *

2434Rewrite the radicand as a product usingthe greatest perfect fourth power factor.81·3434=81Rewrite the radical as the product of tworadicals814·34Simplify.334

Simplify: 288

813

644.

122

333

244

Simplify: 432

6253

7294.

123

553

394

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.

Simplify: x3

x43

x74.

* * *

x3Rewrite the radicand as a product usingthe largest perfect square factor.x2·xRewrite the radical as the product of tworadicals.x2·xSimplify.\|x\|x

* * *

x43 Rewrite the radicand as a productusing the largest perfect cube factor.x3·x3. Rewrite the radical as the product of tworadicals.x33·x3 Simplify.xx3

* * *

x74Rewrite the radicand as a productusing the greatest perfect fourth powerx4·x34factor.Rewrite the radical as the product of tworadicals.x44·x34Simplify.\|x\|x34

Simplify: b5

y64

z53

b2b

\|y\|y24

zz23

Simplify: p9

y85

q136

p4p

pp35


q2q6

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.

Simplify: 72n7

24x73

80y144.

* * *

72n7 Rewrite the radicand as a productusing the largest perfect square factor.36n6·2n Rewrite the radical as the product of tworadicals.36n6·2n Simplify.6\|n3\|2n

* * *

24x73Rewrite the radicand as a productusing perfect cube factors.8x6·3x3Rewrite the radical as the product of tworadicals.8x63·3x3Rewrite the first radicand as(2x2)3.(2x2)33·3x3Simplify.2x23x3

* * *

80y144Rewrite the radicand as a productusing perfect fourth power factors.16y12·5y24Rewrite the radical as the product of tworadicals.16y124·5y24Rewrite the first radicand as(2y3)4.(2y3)44·5y24Simplify.2\|y3\|5y24

Simplify: 32y5

54p103

64q104.

4y22y

3p32p3


2q24q24

Simplify: 75a9

128m113

162n74.

5a43a

4m32m23


3\|n\|2n34

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

Simplify: 63u3v5

40x4y53

48x4y74.

* * *

63u3v5Rewrite the radicand as a productusing the largest perfect square factor.9u2v4·7uvRewrite the radical as the product of tworadicals.9u2v4·7uvRewrite the first radicand as(3uv2)2.(3uv2)2·7uvSimplify.3\|u\|v27uv

* * *

40x4y53Rewrite the radicand as a productusing the largest perfect cube factor.8x3y3·5xy23Rewrite the radical as the product of tworadicals.8x3y33·5xy23Rewrite the first radicand as(2xy)3.(2xy)33·5xy23Simplify.2xy5xy23

* * *

48x4y74Rewrite the radicand as a productusing the largest perfect fourth power16x4y4·3y34factor.Rewrite the radical as the product of tworadicals.16x4y44·3y34Rewrite the first radicand as(2xy)4.(2xy)44·3y34Simplify.2\|xy\|3y34

Simplify: 98a7b5

56x5y43

32x5y84.

7\|a3\|b22ab


2xy7x2y3

2\|x\|y22x4

Simplify: 180m9n11

72x6y53

80x7y44.

6m4\|n5\|5mn


2x2y9y23

2\|xy\|5x34

Simplify: −273

−164.

* * *

−273Rewrite the radicand as a product usingperfect cube factors.(−3)33Take the cube root.−3

* * *

−164There is no real numbernwheren4=−16.Not a real number.

Simplify: −643

−814.

−4

no real number

Simplify: −6253

−3244.

−553

no real number

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.

Simplify: 3+32

4482.

* * *

3+32Rewrite the radicand as a product usingthe largest perfect square factor.3+16·2Rewrite the radical as the product of tworadicals.3+16·2Simplify.3+42

The terms cannot be added as one has a radical and the other does not. Trying to add an integer and a radical is like trying to add an integer and a variable. They are not like terms!

* * *

4482Rewrite the radicand as a productusing the largest perfect square factor.416·32Rewrite the radical as the product of tworadicals.416·32Simplify.4432Factor the common factor from thenumerator.4(13)2Remove the common factor, 2, from thenumerator and denominator.2·2(13)2Simplify.2(13)

Simplify: 5+75

10755

5+53

23

Simplify: 2+98

6453

2+72

25

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.

Simplify: 4580

16543

5804.

* * *

4580Simplify inside the radical first.Rewrite showing the common factors ofthe numerator and denominator.5·95·16Simplify the fraction by removingcommon factors.916Simplify. Note(34)2=916.34

* * *

16543Simplify inside the radical first.Rewrite showing the common factors ofthe numerator and denominator.2·82·273Simplify the fraction by removingcommon factors.8273Simplify. Note(23)3=827.23

* * *

5804Simplify inside the radical first.Rewrite showing the common factors ofthe numerator and denominator.5·15·164Simplify the fraction by removingcommon factors.1164Simplify. Note(12)4=116.12

Simplify: 7548

542503

321624.

54

35

23

Simplify: 98162

243753

43244.

79

25

13

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

Simplify: m6m4

a8a53

a10a24.

* * *

m6m4Simplify the fraction inside the radical first.Divide the like bases by subtracting theexponents.m2Simplify.\|m\|

* * *

a8a53Use the Quotient Property of exponents tosimplify the fraction under the radical first.a33Simplify.a

* * *

a10a24Use the Quotient Property of exponents tosimplify the fraction under the radical first.a84Rewrite the radicand using perfectfourth power factors.(a2)44Simplify.a2

Simplify: a8a6

x7x34

y17y54.

\|a\|

\|x\|

y3

Simplify: x14x10

m13m73

n12n25.

x2

m2

n2

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.

Quotient Property of Radical Expressions

If an

and bn

are real numbers,b0,

and for any integer n2

then,

abn=anbnandanbn=abn
How to Simplify the Quotient of Radical Expressions

Simplify: 27m3196.

![The first step in the process is to simplify the fraction in the radicand, if possible. In this example the quantity 27 m cubed in parentheses divided by 196 cannot be simplified.](/algebra-intermediate-book/resources/CNX_IntAlg_Figure_08_02_002a_img.jpg) ![The second step in the process is to use the quotient property to rewrite the radical as the quotient of two radicals. We rewrite the square root of the quantity 27 m cubed divided by 196 in parentheses as the quotient of the square root of the quantity 27 m cubed in parentheses and the square root of 196.](/algebra-intermediate-book/resources/CNX_IntAlg_Figure_08_02_002b_img.jpg) ![The third step is to simplify the radicals in the numerator and the denominator. 9 m squared and 196 are perfect squares. We rewrite the expression as the quantity square root of quantity 9 m squared in parentheses times square root of the quantity 3 m in parentheses in parentheses divided by square root of 196. The simplified version is the quantity 3 m times square root of the quantity 3 m in parentheses in parentheses divided by 14.](/algebra-intermediate-book/resources/CNX_IntAlg_Figure_08_02_002c_img.jpg)

Simplify: 24p349.

2\|p\|6p7

Simplify: 48x5100.

2x23x5
Simplify a square root 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.

Simplify: 45x5y4

24x7y33

48x10y84.

* * *

45x5y4We cannot simplify the fraction in theradicand. Rewrite using the QuotientProperty.45x5y4Simplify the radicals in the numerator andthe denominator.9x4·5xy2Simplify.3x25xy2

* * *

24x7y33The fraction in the radicand cannot besimplified. Use the Quotient Property towrite as two radicals.24x73y33Rewrite each radicand as a productusing perfect cube factors.8x6·3x3y33Rewrite the numerator as the product oftwo radicals.(2x2)33·3x3y33Simplify.2x23x3y

* * *

48x10y84The fraction in the radicand cannot besimplified.48x104y84Use the Quotient Property to write as tworadicals. Rewrite each radicand as aproduct using perfect fourth power factors.16x8·3x24y84Rewrite the numerator as the product oftwo radicals.(2x2)44·3x24(y2)44Simplify.2x23x24y2

Simplify: 80m3n6

108c10d63

80x10y44.

4\|m\|5m\|n3\|

3c34c3d2


2x25x24\|y\|

Simplify: 54u7v8

40r3s63

162m14n124.

3u36uv4

2r53s2


3\|m3\|2m24\|n3\|

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

Simplify: 18p5q732pq2

16x5y754x2y23

5a8b680a3b24.

* * *

18p5q732pq2Simplify the fraction in the radicand, ifpossible.9p4q516Rewrite using the Quotient Property.9p4q516Simplify the radicals in the numerator andthe denominator.9p4q4·q4Simplify.3p2q2q4

* * *

16x5y754x2y23Simplify the fraction in the radicand, ifpossible.8x3y5273Rewrite using the Quotient Property.8x3y53273Simplify the radicals in the numerator andthe denominator.8x3y33·y23273Simplify.2xyy233

* * *

5a8b680a3b24Simplify the fraction in the radicand, ifpossible.a5b4164Rewrite using the Quotient Property.a5b44164Simplify the radicals in the numerator andthe denominator.a4b44·a4164Simplify.\|ab\|a42

Simplify: 50x5y372x4y

16x5y754x2y23

5a8b680a3b24.

5\|y\|x6

2xyy233


\|ab\|a42

Simplify: 48m7n2100m5n8

54x7y5250x2y23

32a9b7162a3b34.

2\|m\|35\|n3\|

3xyx235


2\|ab\|a243

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.

Simplify: 48a73a

−108323

96x743x24.

* * *

48a73aThe denominator cannot be simplified, souse the Quotient Property to write as oneradical.48a73aSimplify the fraction under the radical.16a6Simplify.4\|a3\|

* * *

−108323The denominator cannot be simplified, souse the Quotient Property to write as oneradical.−10823Simplify the fraction under the radical.−543Rewrite the radicand as a product usingperfect cube factors.(−3)3·23Rewrite the radical as the product of tworadicals.(−3)33·23Simplify.−323

* * *

96x743x24The denominator cannot be simplified, souse the Quotient Property to write as oneradical.96x73x24Simplify the fraction under the radical.32x54Rewrite the radicand as a product usingperfect fourth power factors.16x44·2x4Rewrite the radical as the product of tworadicals.(2x)44·2x4Simplify.2\|x\|2x4

Simplify: 98z52z

−500323

486m1143m54.

7z2

−523


3\|m\|2m24

Simplify: 128m92m

−192333

324n742n34.

8m4

−4

3\|n\|24

Access these online resources for additional instruction and practice with simplifying radical expressions.

Key Concepts

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

324

645

224

225

6253

1286

645

2563

225

443

31254

813

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


y11


r53


s104

\| y5 \|y

rr23

s2s24


m13


u75


v116


n21


q83


n108

n10n

q2q23


\|n\|n28


r25


p85


m54


125r13


108x53


48y64

5r65r

3x4x23


2\|y\|3y24


80s15


96a75


128b76


242m23


405m104


160n85

11\|m11\|2m

3m25m24

2n5n35


175n13


512p55


324q74


147m7n11


48x6y73


32x5y44

7\|m3n5\|3mn

2x2y26y3

2\|xy\|2x4


96r3s3


80x7y63


80x8y94


192q3r7


54m9n103


81a9b84

8\|qr3\|3qr

3m3n32n3

3a2b2a4


150m9n3


81p7q83


162c11d124


−8643


−2564

−643

not real


−4865


−646


−325


−18

−2

not real


−83


−164


5+12


10242

5+23

56


8+96


8804


1+45


3+903

1+35

1+10


3+125


15+755

Use the Quotient Property to Simplify Radical Expressions

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

4580

8273

1814

34

23

13

7298

24813

6964

10036

813753

12564

53

35

14

12116

162503

321624

x10x6

p11p23

q17q134

x2

p3

\|q\|

p20p10

d12d75

m12m48

y4y8

u21u115

v30v126

1y2

u2

\|v3\|

q8q14

r14r53

c21c94

96x7121
4\|x3\|6x11
108y449
300m564
10m23m8
125n7169
98r5100
7r22r10
180s10144
28q6225
2\|q3\|715
150r3256

75r9s8


54a8b33


64c5d44

5r43rs4

3a22a23\|b\|


2\|c\|4c4\|d\|


72x5y6


96r11s55


128u7v126


28p7q2


81s8t33


64p15q124

2\|p3\|7p\|q\|

3s23s23t


2\|p3\|4p34\|q3\|


45r3s10


625u10v33


729c21d84


32x5y318x3y


5x6y940x5y33


5a8b680a3b24

4\|xy\|3

y2x32

\|ab\|a44


75r6s848rs4


24x8y481x2y3


32m9n2162mn24


27p2q108p4q3


16c5d7250c2d23


2m9n7128m3n6

12\|pq\|

2cd2d255


\|mn\|262


50r5s2128r2s6


24m9n7375m4n3


81m2n8256m1n24


45p95q2


64424


128x852x25

3p4p\|q\|

224


2x2x5


80q55q


−625353


80m745m4


50m72m


125023


486y92y34

5\|m3\|

553


3\|y\|3y24


72n112n


16263


160r105r34

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?


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