Elementary Algebra

# 6.5Divide Monomials

Elementary Algebra6.5 Divide Monomials

### Learning Objectives

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

• Simplify expressions using the Quotient Property for Exponents
• Simplify expressions with zero exponents
• Simplify expressions using the quotient to a Power Property
• Simplify expressions by applying several properties
• Divide monomials
Be Prepared 6.5

Before you get started, take this readiness quiz.

1. Simplify: $824.824.$
If you missed this problem, review Example 1.65.
2. Simplify: $(2m3)5.(2m3)5.$
If you missed this problem, review Example 6.23.
3. Simplify: $12x12y.12x12y.$
If you missed this problem, review Example 1.67.

### Simplify Expressions Using the Quotient Property for Exponents

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

### Summary of Exponent Properties for Multiplication

If $aandbaandb$ are real numbers, and $mandnmandn$ are whole numbers, then

 Product Property $am·an=am+nam·an=am+n$ Power Property $(am)n=am·n(am)n=am·n$ Product to a Power $(ab)m=ambm(ab)m=ambm$

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

### Equivalent Fractions Property

If $a,b,andca,b,andc$ are whole numbers where $b≠0,c≠0b≠0,c≠0$,

$thenab=a·cb·canda·cb·c=abthenab=a·cb·canda·cb·c=ab$

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

 Consider $x5x2x5x2$ and $x2x3x2x3$ What do they mean? $x·x·x·x·xx·xx·x·x·x·xx·x$ $x·xx·x·xx·xx·x·x$ Use the Equivalent Fractions Property. $x·x·x·x·xx·xx·x·x·x·xx·x$ $x·x·1x·x·xx·x·1x·x·x$ Simplify. $x3x3$ $1x1x$

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

When the larger exponent was in the numerator, we were left with factors in the numerator.

When the larger exponent was in the denominator, we were left with factors in the denominator—notice the numerator of 1.

We write:

$x5x2x2x3x5−21x3−2x31xx5x2x2x3x5−21x3−2x31x$

This leads to the Quotient Property for Exponents.

### Quotient Property for Exponents

If $aa$ is a real number, $a≠0a≠0$, and $mandnmandn$ are whole numbers, then

$aman=am−n,m>nandaman=1an−m,n>maman=am−n,m>nandaman=1an−m,n>m$

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

$3432=34−25253=153−2819=3225125=1519=9✓15=15✓3432=34−25253=153−2819=3225125=1519=9✓15=15✓$

### Example 6.59

Simplify: $x9x7x9x7$ $31032.31032.$

Try It 6.117

Simplify: $x15x10x15x10$ $61465.61465.$

Try It 6.118

Simplify: $y43y37y43y37$ $1015107.1015107.$

### Example 6.60

Simplify: $b8b12b8b12$ $7375.7375.$

Try It 6.119

Simplify: $x18x22x18x22$ $12151230.12151230.$

Try It 6.120

Simplify: $m7m15m7m15$ $98919.98919.$

Notice the difference in the two previous examples:

• If we start with more factors in the numerator, we will end up with factors in the numerator.
• If we start with more factors in the denominator, we will end up with factors in the denominator.

The first step in simplifying an expression using the Quotient Property for Exponents is to determine whether the exponent is larger in the numerator or the denominator.

### Example 6.61

Simplify: $a5a9a5a9$ $x11x7.x11x7.$

Try It 6.121

Simplify: $b19b11b19b11$ $z5z11.z5z11.$

Try It 6.122

Simplify: $p9p17p9p17$ $w13w9.w13w9.$

### Simplify Expressions with an Exponent of Zero

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

$22=11717=1−43−43=122=11717=1−43−43=1$

In words, a number divided by itself is 1. So, $xx=1xx=1$, for any $x(x≠0)x(x≠0)$, since any number divided by itself is 1.

The Quotient Property for Exponents shows us how to simplify $amanaman$ when $m>nm>n$ and when $n by subtracting exponents. What if $m=nm=n$?

Consider $8888$, which we know is 1.

 $88=188=1$ Write $88$ as $2323$. $2323=12323=1$ Subtract exponents. $23−3=123−3=1$ Simplify. $20=120=1$

Now we will simplify $amamamam$ in two ways to lead us to the definition of the zero exponent. In general, for $a≠0a≠0$:

We see $amamamam$ simplifies to $a0a0$ and to 1. So $a0=1a0=1$.

### Zero Exponent

If $aa$ is a non-zero number, then $a0=1a0=1$.

Any nonzero number raised to the zero power is 1.

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

### Example 6.62

Simplify: $9090$ $n0.n0.$

Try It 6.123

Simplify: $150150$ $m0.m0.$

Try It 6.124

Simplify: $k0k0$ $290.290.$

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 $(2x)0(2x)0$. We can use the product to a power rule to rewrite this expression.

 $(2x)0(2x)0$ Use the product to a power rule. $20x020x0$ Use the zero exponent property. $1·11·1$ Simplify. $11$
Table 6.1

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

### Example 6.63

Simplify: $(5b)0(5b)0$ $(−4a2b)0.(−4a2b)0.$

Try It 6.125

Simplify: $(11z)0(11z)0$ $(−11pq3)0.(−11pq3)0.$

Try It 6.126

Simplify: $(−6d)0(−6d)0$ $(−8m2n3)0.(−8m2n3)0.$

### 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.

 $(xy)3(xy)3$ This means: $xy·xy·xyxy·xy·xy$ Multiply the fractions. $x·x·xy·y·yx·x·xy·y·y$ Write with exponents. $x3y3x3y3$

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

 We write: $(xy)3(xy)3$ $x3y3x3y3$

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

### Quotient to a Power Property for Exponents

If $aa$ and $bb$ are real numbers, $b≠0b≠0$, and $mm$ is a counting number, then

$(ab)m=ambm(ab)m=ambm$

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

$(23)3=233323·23·23=827827=827✓(23)3=233323·23·23=827827=827✓$

### Example 6.64

Simplify: $(37)2(37)2$ $(b3)4(b3)4$ $(kj)3.(kj)3.$

Try It 6.127

Simplify: $(58)2(58)2$ $(p10)4(p10)4$ $(mn)7.(mn)7.$

Try It 6.128

Simplify: $(13)3(13)3$ $(−2q)3(−2q)3$ $(wx)4.(wx)4.$

### 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.

### Summary of Exponent Properties

If $aandbaandb$ are real numbers, and $mandnmandn$ are whole numbers, then

 Product Property $am·an=am+nam·an=am+n$ Power Property $(am)n=am·n(am)n=am·n$ Product to a Power $(ab)m=ambm(ab)m=ambm$ Quotient Property $ambm=am−n,a≠0,m>n aman=1an−m,a≠0,n>m ambm=am−n,a≠0,m>n aman=1an−m,a≠0,n>m$ Zero Exponent Definition $ao=1,a≠0ao=1,a≠0$ Quotient to a Power Property $(ab)m=ambm,b≠0(ab)m=ambm,b≠0$

### Example 6.65

Simplify: $(y4)2y6.(y4)2y6.$

Try It 6.129

Simplify: $(m5)4m7.(m5)4m7.$

Try It 6.130

Simplify: $(k2)6k7.(k2)6k7.$

### Example 6.66

Simplify: $b12(b2)6.b12(b2)6.$

Try It 6.131

Simplify: $n12(n3)4.n12(n3)4.$

Try It 6.132

Simplify: $x15(x3)5.x15(x3)5.$

### Example 6.67

Simplify: $(y9y4)2.(y9y4)2.$

Try It 6.133

Simplify: $(r5r3)4.(r5r3)4.$

Try It 6.134

Simplify: $(v6v4)3.(v6v4)3.$

### Example 6.68

Simplify: $(j2k3)4.(j2k3)4.$

Try It 6.135

Simplify: $(a3b2)4.(a3b2)4.$

Try It 6.136

Simplify: $(q7r5)3.(q7r5)3.$

### Example 6.69

Simplify: $(2m25n)4.(2m25n)4.$

Try It 6.137

Simplify: $(7x39y)2.(7x39y)2.$

Try It 6.138

Simplify: $(3x47y)2.(3x47y)2.$

### Example 6.70

Simplify: $(x3)4(x2)5(x6)5.(x3)4(x2)5(x6)5.$

Try It 6.139

Simplify: $(a2)3(a2)4(a4)5.(a2)3(a2)4(a4)5.$

Try It 6.140

Simplify: $(p3)4(p5)3(p7)6.(p3)4(p5)3(p7)6.$

### Example 6.71

Simplify: $(10p3)2(5p)3(2p5)4.(10p3)2(5p)3(2p5)4.$

Try It 6.141

Simplify: $(3r3)2(r3)7(r3)3.(3r3)2(r3)7(r3)3.$

Try It 6.142

Simplify: $(2x4)5(4x3)2(x3)5.(2x4)5(4x3)2(x3)5.$

### Divide Monomials

You have now been introduced to all the properties of exponents and used them to simplify expressions. Next, you’ll see how to use these properties to divide monomials. Later, you’ll use them to divide polynomials.

### Example 6.72

Find the quotient: $56x7÷8x3.56x7÷8x3.$

Try It 6.143

Find the quotient: $42y9÷6y3.42y9÷6y3.$

Try It 6.144

Find the quotient: $48z8÷8z2.48z8÷8z2.$

### Example 6.73

Find the quotient: $45a2b3−5ab5.45a2b3−5ab5.$

Try It 6.145

Find the quotient: $−72a7b38a12b4.−72a7b38a12b4.$

Try It 6.146

Find the quotient: $−63c8d37c12d2.−63c8d37c12d2.$

### Example 6.74

Find the quotient: $24a5b348ab4.24a5b348ab4.$

Try It 6.147

Find the quotient: $16a7b624ab8.16a7b624ab8.$

Try It 6.148

Find the quotient: $27p4q7−45p12q.27p4q7−45p12q.$

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.

### Example 6.75

Find the quotient: $14x7y1221x11y6.14x7y1221x11y6.$

Try It 6.149

Find the quotient: $28x5y1449x9y12.28x5y1449x9y12.$

Try It 6.150

Find the quotient: $30m5n1148m10n14.30m5n1148m10n14.$

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. This follows the order of operations. Remember, a fraction bar is a grouping symbol.

### Example 6.76

Find the quotient: $(6x2y3)(5x3y2)(3x4y5).(6x2y3)(5x3y2)(3x4y5).$

Try It 6.151

Find the quotient: $(6a4b5)(4a2b5)12a5b8.(6a4b5)(4a2b5)12a5b8.$

Try It 6.152

Find the quotient: $(−12x6y9)(−4x5y8)−12x10y12.(−12x6y9)(−4x5y8)−12x10y12.$

### Media

Access these online resources for additional instruction and practice with dividing monomials:

### Section 6.5 Exercises

#### Practice Makes Perfect

Simplify Expressions Using the Quotient Property for Exponents

In the following exercises, simplify.

356.

$x18x3x18x3$ $5125351253$

357.

$y20y10y20y10$ $7167271672$

358.

$p21p7p21p7$ $4164441644$

359.

$u24u3u24u3$ $9159591595$

360.

$q18q36q18q36$ $102103102103$

361.

$t10t40t10t40$ $83858385$

362.

$bb9bb9$ $446446$

363.

$xx7xx7$ $1010310103$

Simplify Expressions with Zero Exponents

In the following exercises, simplify.

364.

$200200$
$b0b0$

365.

$130130$
$k0k0$

366.

$−270−270$
$−(270)−(270)$

367.

$−150−150$
$−(150)−(150)$

368.

$(25x)0(25x)0$
$25x025x0$

369.

$(6y)0(6y)0$
$6y06y0$

370.

$(12x)0(12x)0$
$(−56p4q3)0(−56p4q3)0$

371.

$7y07y0$$(17y)0(17y)0$
$(−93c7d15)0(−93c7d15)0$

372.

$12n0−18m012n0−18m0$
$(12n)0−(18m)0(12n)0−(18m)0$

373.

$15r0−22s015r0−22s0$
$(15r)0−(22s)0(15r)0−(22s)0$

Simplify Expressions Using the Quotient to a Power Property

In the following exercises, simplify.

374.

$(34)3(34)3$ $(p2)5(p2)5$ $(xy)6(xy)6$

375.

$(25)2(25)2$ $(x3)4(x3)4$ $(ab)5(ab)5$

376.

$(a3b)4(a3b)4$ $(54m)2(54m)2$

377.

$(x2y)3(x2y)3$ $(103q)4(103q)4$

Simplify Expressions by Applying Several Properties

In the following exercises, simplify.

378.

$(a2)3a4(a2)3a4$

379.

$(p3)4p5(p3)4p5$

380.

$(y3)4y10(y3)4y10$

381.

$(x4)5x15(x4)5x15$

382.

$u6(u3)2u6(u3)2$

383.

$v20(v4)5v20(v4)5$

384.

$m12(m8)3m12(m8)3$

385.

$n8(n6)4n8(n6)4$

386.

$(p9p3)5(p9p3)5$

387.

$(q8q2)3(q8q2)3$

388.

$(r2r6)3(r2r6)3$

389.

$(m4m7)4(m4m7)4$

390.

$(pr11)2(pr11)2$

391.

$(ab6)3(ab6)3$

392.

$(w5x3)8(w5x3)8$

393.

$(y4z10)5(y4z10)5$

394.

$(2j33k)4(2j33k)4$

395.

$(3m55n)3(3m55n)3$

396.

$(3c24d6)3(3c24d6)3$

397.

$(5u72v3)4(5u72v3)4$

398.

$(k2k8k3)2(k2k8k3)2$

399.

$(j2j5j4)3(j2j5j4)3$

400.

$(t2)5(t4)2(t3)7(t2)5(t4)2(t3)7$

401.

$(q3)6(q2)3(q4)8(q3)6(q2)3(q4)8$

402.

$(−2p2)4(3p4)2(−6p3)2(−2p2)4(3p4)2(−6p3)2$

403.

$(−2k3)2(6k2)4(9k4)2(−2k3)2(6k2)4(9k4)2$

404.

$(−4m3)2(5m4)3(−10m6)3(−4m3)2(5m4)3(−10m6)3$

405.

$(−10n2)3(4n5)2(2n8)2(−10n2)3(4n5)2(2n8)2$

Divide Monomials

In the following exercises, divide the monomials.

406.

$56b8÷ 7b256b8÷ 7b2$

407.

$63v10÷ 9v263v10÷ 9v2$

408.

$−88y15÷ 8y3−88y15÷ 8y3$

409.

$−72u12÷ 12u4−72u12÷ 12u4$

410.

$45a6b8−15a10b245a6b8−15a10b2$

411.

$54x9y3−18x6y1554x9y3−18x6y15$

412.

$15r4s918r9s215r4s918r9s2$

413.

$20m8n430m5n920m8n430m5n9$

414.

$18a4b8−27a9b518a4b8−27a9b5$

415.

$45x5y9−60x8y645x5y9−60x8y6$

416.

$64q11r9s348q6r8s564q11r9s348q6r8s5$

417.

$65a10b8c542a7b6c865a10b8c542a7b6c8$

418.

$(10m5n4)(5m3n6)25m7n5(10m5n4)(5m3n6)25m7n5$

419.

$(−18p4q7)(−6p3q8)−36p12q10(−18p4q7)(−6p3q8)−36p12q10$

420.

$(6a4b3)(4ab5)(12a2b)(a3b)(6a4b3)(4ab5)(12a2b)(a3b)$

421.

$(4u2v5)(15u3v)(12u3v)(u4v)(4u2v5)(15u3v)(12u3v)(u4v)$

Mixed Practice

422.

$24a5+2a524a5+2a5$
$24a5−2a524a5−2a5$
$24a5·2a524a5·2a5$
$24a5÷2a524a5÷2a5$

423.

$15n10+3n1015n10+3n10$
$15n10−3n1015n10−3n10$
$15n10·3n1015n10·3n10$
$15n10÷3n1015n10÷3n10$

424.

$p4·p6p4·p6$
$(p4)6(p4)6$

425.

$q5·q3q5·q3$
$(q5)3(q5)3$

426.

$y3yy3y$
$yy3yy3$

427.

$z6z5z6z5$
$z5z6z5z6$

428.

$(8x5)(9x)÷6x3(8x5)(9x)÷6x3$

429.

$(4y)(12y7)÷8y2(4y)(12y7)÷8y2$

430.

$27a73a3+54a99a527a73a3+54a99a5$

431.

$32c114c5+42c96c332c114c5+42c96c3$

432.

$32y58y2−60y105y732y58y2−60y105y7$

433.

$48x66x4−35x97x748x66x4−35x97x7$

434.

$63r6s39r4s2−72r2s26s63r6s39r4s2−72r2s26s$

435.

$56y4z57y3z3−45y2z25y56y4z57y3z3−45y2z25y$

#### Everyday Math

436.

Memory One megabyte is approximately $106106$ bytes. One gigabyte is approximately $109109$ bytes. How many megabytes are in one gigabyte?

437.

Memory One gigabyte is approximately $109109$ bytes. One terabyte is approximately $10121012$ bytes. How many gigabytes are in one terabyte?

#### Writing Exercises

438.

Jennifer thinks the quotient $a24a6a24a6$ simplifies to $a4a4$. What is wrong with her reasoning?

439.

Maurice simplifies the quotient $d7dd7d$ by writing $d7 d=7 d7 d=7$. What is wrong with his reasoning?

440.

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

441.

Robert thinks $x0x0$ simplifies to 0. What would you say to convince Robert he is wrong?

#### Self Check

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

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?

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