Prealgebra 2e · free preview

10.4 Divide Monomials

Learning objectives: Simplify expressions using the Quotient Property of Exponents; Simplify expressions with zero exponents; Simplify expressions using the Quotient to a Power Property; Simplify expressions by applying several properties; Divide monomials

1. Learning objectives

Learning objectives

Learning objectives

  • Simplify expressions using the Quotient Property of Exponents
  • Simplify expressions with zero exponents
  • Simplify expressions using the Quotient to a Power Property
  • Simplify expressions by applying several properties
  • Divide monomials

2. Simplify Expressions Using the Quotient Property of Exponents

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.

If a, ba,\,b are real numbers and m, nm,\,n are whole numbers, then

ProductPropertyam⋅an=am+nPowerProperty (am)n=am⋅nProducttoaPower (ab)m=ambm\begin{array}{lccc} \mathrm{Product Property} & & & {a}^{m}\cdot{a}^{n}={a}^{m+n} \\ \mathrm{Power Property} & & & \,{({a}^{m})}^{n}={a}^{m\cdot{}n} \\ \mathrm{Product to a Power} & & & \,{(ab)}^{m}={a}^{m}{b}^{m} \\ \end{array}

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.

If a, b, ca,\,b,\,c are whole numbers where b≠0, c≠0,b\ne{}0,\,c\ne{}0, then

ab=a ⋅ cb ⋅ c and a ⋅ cb ⋅ c=ab\frac{a}{b}=\frac{a\,\cdot\,c}{b\,\cdot\,c}\,\mathrm{and}\,\frac{a\,\cdot\,c}{b\,\cdot\,c}=\frac{a}{b}

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

Considerx5x2andx2x3Whatdotheymean?x⋅x⋅x⋅x⋅xx⋅xx⋅xx⋅x⋅xUsetheEquivalentFractionsProperty.x⋅x⋅x⋅x⋅xx⋅x⋅1x⋅x⋅1x⋅x⋅xSimplify.x31x\begin{array}{lccccclccc} \mathrm{Consider} & & & \frac{{x}^{5}}{{x}^{2}} & & & \mathrm{and} & & & \frac{{x}^{2}}{{x}^{3}} \\ \mathrm{What do they mean?} & & & \frac{x\cdot{}x\cdot{}x\cdot{}x\cdot{}x}{x\cdot{}x} & & & & & & \frac{x\cdot{}x}{x\cdot{}x\cdot{}x} \\ \mathrm{Use the Equivalent Fractions Property.} & & & \frac{x\cdot{}x\cdot{}x\cdot{}x\cdot{}x}{x\cdot{}x\cdot{}1} & & & & & & \frac{x\cdot{}x\cdot{}1}{x\cdot{}x\cdot{}x} \\ \mathrm{Simplify.} & & & {x}^{3} & & & & & & \frac{1}{x} \\ \end{array}

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 11 in the denominator, which we simplified.
  • When the larger exponent was in the denominator, we were left with factors in the denominator, and 11 in the numerator, which could not be simplified.

We write:

x5x2 x2x3x5−2 1x3−2x3 1x\begin{array}{lcccc} \frac{{x}^{5}}{{x}^{2}} & \, & & & \frac{{x}^{2}}{{x}^{3}} \\ {x}^{5-2} & \, & & & \frac{1}{{x}^{3-2}} \\ {x}^{3} & \, & & & \frac{1}{x} \\ \end{array}

If aa is a real number, a≠0,a\ne{}0, and m, nm,\,n are whole numbers, then

aman=am−n, m>n and aman=1an−m, n>m\frac{{a}^{m}}{{a}^{n}}={a}^{m-n},\,m>n\,\mathrm{and}\,\frac{{a}^{m}}{{a}^{n}}=\frac{1}{{a}^{n-m}},\,n>m

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

3432=?34−2 5253=?153−2819=?3225125=?151 9=9✓ 15=15✓\begin{array}{lccc} \frac{{3}^{4}}{{3}^{2}}\overset{?}{=}{3}^{4-2} & & & \,\frac{{5}^{2}}{{5}^{3}}\overset{?}{=}\frac{1}{{5}^{3-2}} \\ \frac{81}{9}\overset{?}{=}{3}^{2} & & & \frac{25}{125}\overset{?}{=}\frac{1}{{5}^{1}} \\ \,9=9\mathrm{✓} & & & \,\frac{1}{5}=\frac{1}{5}\mathrm{✓} \\ \end{array}

When we work with numbers and the exponent is less than or equal to 3,3, we will apply the exponent. When the exponent is greater than 33, we leave the answer in exponential form.

3. Example 10.45

Example 10.45

Example 10.45

Simplify:

  1. ⓐ  x10x8\,\frac{{x}^{10}}{{x}^{8}}
  2. ⓑ  2922\,\frac{{2}^{9}}{{2}^{2}}

Solution

  1. Apply the quotient property. For powers with the same base, subtract the denominator exponent from the numerator exponent.
  2. Simplify part ⓐ. The exponent difference is 10−8=210-8=2, so x10x8=x2\frac{x^{10}}{x^8}=x^2.
  3. Simplify part ⓑ. The exponent difference is 9−2=79-2=7, so 2922=27\frac{2^9}{2^2}=2^7.

Takeaway: For a quotient with the same base, subtract the denominator exponent from the numerator exponent, so x10/x8=x2x^{10}/x^8=x^2 and 29/22=272^9/2^2=2^7.

4. Example 10.46

Example 10.46

Example 10.46

Simplify:

  1. ⓐ  b10b15\,\frac{{b}^{10}}{{b}^{15}}
  2. ⓑ  3335\,\frac{{3}^{3}}{{3}^{5}}

Solution

  1. Compare the exponents in each quotient. A larger denominator exponent leaves a negative exponent difference, which must be rewritten as a reciprocal.
  2. Simplify part ⓐ. The difference 10−15=−510-15=-5 gives b−5=1b5b^{-5}=\frac{1}{b^5}.
  3. Simplify part ⓑ. The difference 3−5=−23-5=-2 gives 3−2=132=193^{-2}=\frac{1}{3^2}=\frac{1}{9}.

Takeaway: When the denominator has the larger exponent in a same-base quotient, the result is 11 divided by the remaining base power, giving 1/b51/b^5 and 1/91/9.

5. Example 10.47

Example 10.47

Example 10.47

Simplify:

  1. ⓐ  a5a9\,\frac{{a}^{5}}{{a}^{9}}
  2. ⓑ  x11x7\,\frac{{x}^{11}}{{x}^{7}}

Solution

  1. Apply the quotient property to part ⓐ. Since both powers have base aa, subtract the denominator exponent from the numerator exponent: a5a9=a5−9=a−4\frac{{a}^{5}}{{a}^{9}}=a^{5-9}=a^{-4}.
  2. Rewrite the negative exponent as a reciprocal. Using a−n=1ana^{-n}=\frac{1}{a^n} gives 1a4\frac{1}{a^4}. The first figure shows this reciprocal form as 1a9−5\frac{1}{a^{9-5}}.
  3. Apply the quotient property to part ⓑ. The common base is xx, so x11x7=x11−7=x4\frac{{x}^{11}}{{x}^{7}}=x^{11-7}=x^4. The second figure displays the exponent difference 11−711-7.
  4. State both results. Part ⓐ is 1a4\frac{1}{a^4} and part ⓑ is x4x^4.

Takeaway: When dividing equal bases, subtract the denominator exponent and interpret any negative result by placing the base in the denominator.

6. Simplify Expressions with Zero Exponents

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.\frac{{a}^{m}}{{a}^{m}}. From earlier work with fractions, we know that

22=1 1717=1 −43−43=1\frac{2}{2}=1\,\frac{17}{17}=1\,\frac{-43}{-43}=1

In words, a number divided by itself is 1.1. So xx=1,\frac{x}{x}=1, for any xx (x≠0x\ne{}0), since any number divided by itself is 1.1.

The Quotient Property of Exponents shows us how to simplify aman\frac{{a}^{m}}{{a}^{n}} when m>nm>n and when n<mn<m by subtracting exponents. What if m=nm=n?

Now we will simplify amam\frac{{a}^{m}}{{a}^{m}} in two ways to lead us to the definition of the zero exponent.

Consider first 88,\frac{8}{8}, which we know is 1.1.

88=1\frac{8}{8}=1
Write 8 as 23{2}^{3}.2323=1\frac{{2}^{3}}{{2}^{3}}=1
Subtract exponents.23−3=1{2}^{3-3}=1
Simplify.20=1{2}^{0}=1

We see aman\frac{{a}^{m}}{{a}^{n}} simplifies to a a0{a}^{0} and to 11. So a0=1{a}^{0}=1.

If aa is a non-zero number, then a0=1.{a}^{0}=1. Any nonzero number raised to the zero power is 1.1.

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

7. Example 10.48

Example 10.48

Example 10.48

Simplify:

  1. ⓐ  120\,{12}^{0}
  2. ⓑ  y0\,{y}^{0}

Solution

  1. State the zero-exponent rule. Every nonzero number raised to the zero power equals 11, regardless of the base or its magnitude.
  2. Simplify part ⓐ. Since 1212 is nonzero, 120=112^0=1 regardless of whether the base is greater or less than 11.
  3. Simplify part ⓑ. Under the usual assumption that y≠0y\ne0, y0=1y^0=1, so both expressions simplify to 11.

Takeaway: Every nonzero base raised to the zero power equals 1, so 120=112^0=1 and y0=1y^0=1.

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.20x0{2}^{0}{x}^{0}
Use the Zero Exponent Property.1⋅11\cdot{}1
Simplify.1

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

8. Example 10.49

Example 10.49

Example 10.49

Simplify: (7z)0.{(7z)}^{0}.

Solution

  1. Identify the complete base. The zero exponent applies to the entire nonzero product 7z7z, not merely to zz.
  2. Apply the zero-exponent rule. The expression (7z)0(7z)^0 therefore has value 11.
  3. State the simplified result. No coefficient or variable remains because the whole base was raised to the zero power.

Takeaway: Any nonzero expression raised to the zero power equals 1, so (7z)0=1(7z)^0=1.

9. Example 10.50

Example 10.50

Example 10.50

Simplify:

  1. ⓐ  (−3x2y)0\,{(-3{x}^{2}y)}^{0}
  2. ⓑ  −3x2y0\,-3{x}^{2}{y}^{0}

Solution

  1. Locate each zero exponent. In part ⓐ, the exponent applies to the entire product; in part ⓑ, it applies only to yy.
  2. Simplify part ⓐ. The nonzero product (−3x2y)0{(-3{x}^{2}y)}^{0} has value 11 by the zero-exponent rule.
  3. Simplify part ⓑ. Replace y0y^0 with 11, giving −3x2⋅1=−3x2-3x^2\cdot{}1=-3x^2.
  4. Compare the results. The whole base becomes 11 in part ⓐ, while only yy becomes 11 in part ⓑ.

Takeaway: A zero exponent applies only to its own base, so (−3x2y)0=1(-3x^2y)^0=1 while −3x2y0=−3x2-3x^2y^0=-3x^2.

10. Simplify Expressions Using the Quotient to a Power Property

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{(\frac{x}{y})}^{3}
This meansxy⋅xy⋅xy\frac{x}{y}\cdot\frac{x}{y}\cdot\frac{x}{y}
Multiply the fractions.x⋅x⋅xy⋅y⋅y\frac{x\cdot{}x\cdot{}x}{y\cdot{}y\cdot{}y}
Write with exponents.x3y3\frac{{x}^{3}}{{y}^{3}}

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

We see that (xy)3{(\frac{x}{y})}^{3} is x3y3.\frac{{x}^{3}}{{y}^{3}}.

Wewrite:(xy)3x3y3\begin{array}{lcccl} \mathrm{We write:} & & & & {(\frac{x}{y})}^{3} \\ & & & & \frac{{x}^{3}}{{y}^{3}} \\ \end{array}

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

If aa and bb are real numbers, b≠0,b\ne{}0, and mm is a counting number, then

(ab)m= ambm{(\frac{a}{b})}^{m}=\,\frac{{a}^{m}}{{b}^{m}}

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

An example with numbers may help you understand this property:

(23)3=?233323⋅23⋅23=?827827=827✓\begin{array}{rcl} {(\frac{2}{3})}^{3} & \overset{?}{=} & \frac{{2}^{3}}{{3}^{3}} \\ \frac{2}{3}\cdot\frac{2}{3}\cdot\frac{2}{3} & \overset{?}{=} & \frac{8}{27} \\ \frac{8}{27} & = & \frac{8}{27}\mathrm{✓} \\ \end{array}

11. Example 10.51

Example 10.51

Example 10.51

Simplify:

  1. ⓐ  (58)2\,{(\frac{5}{8})}^{2}
  2. ⓑ  (x3)4\,{(\frac{x}{3})}^{4}
  3. ⓒ  (ym)3\,{(\frac{y}{m})}^{3}

Solution

  1. Apply the quotient to a power property to part ⓐ. Raise the numerator and denominator to the second power: (58)2=5282\left(\frac{5}{8}\right)^2=\frac{5^2}{8^2}. The first two figures show the original expression and this separated form, with both exponents highlighted.
  2. Simplify the numerical powers. Since 52=255^2=25 and 82=648^2=64, the fraction becomes 2564\frac{25}{64}, the result shown in the third figure.
  3. Apply the same property to part ⓑ. Raise both parts to the fourth power: (x3)4=x434\left(\frac{x}{3}\right)^4=\frac{x^4}{3^4}. The fourth and fifth figures display this original and separated forms with the exponents 44 highlighted.
  4. Evaluate the denominator. Since 34=813^4=81, part ⓑ simplifies to x481\frac{x^4}{81}, as shown in the sixth figure.
  5. Apply the property to part ⓒ and state the results. Raising both parts to the third power gives y3m3\frac{y^3}{m^3}, with the final two figures showing that separated form and its highlighted exponents. Therefore the three answers are 2564\frac{25}{64}, x481\frac{x^4}{81}, and y3m3\frac{y^3}{m^3}.

Takeaway: Raising a quotient to a power raises the numerator and denominator separately to that same power.

12. Simplify Expressions by Applying Several Properties

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.

If a, ba,\,b are real numbers and m,nm,n are whole numbers, then

ProductPropertyam⋅an=am+nPowerProperty(am)n=am⋅nProducttoaPowerProperty(ab)m=ambmQuotientPropertyaman=am−n,a≠0, m>naman=1an−m,a≠0, n>mZeroExponentDefinitiona0=1, a≠0QuotienttoaPowerProperty(ab)m=ambm, b≠0\begin{array}{lccl} \mathrm{Product Property} & & & {a}^{m}\cdot{a}^{n}={a}^{m+n} \\ \mathrm{Power Property} & & & {({a}^{m})}^{n}={a}^{m\cdot{}n} \\ \mathrm{Product to a Power Property} & & & {(ab)}^{m}={a}^{m}{b}^{m} \\ \mathrm{Quotient Property} & & & \frac{{a}^{m}}{{a}^{n}}={a}^{m-n},a\ne{}0,\,m>n \\ & & & \frac{{a}^{m}}{{a}^{n}}=\frac{1}{{a}^{n-m}},a\ne{}0,\,n>m \\ \mathrm{Zero Exponent Definition} & & & {a}^{0}=1,\,a\ne{}0 \\ \mathrm{Quotient to a Power Property} & & & {(\frac{a}{b})}^{m}=\frac{{a}^{m}}{{b}^{m}},\,b\ne{}0 \\ \end{array}

13. Example 10.52

Example 10.52

Example 10.52

Simplify: (x2)3x5.\frac{{({x}^{2})}^{3}}{{x}^{5}}.

Solution

  1. Simplify the nested power in the numerator. Multiplying exponents gives (x2)3=x2⋅3=x6{({x}^{2})}^{3}=x^{2\cdot{}3}=x^6.
  2. Rewrite the quotient. The expression becomes x6x5\frac{x^6}{x^5}, with matching bases in the numerator and denominator.
  3. Subtract the exponents. The quotient property gives x6−5=x1=xx^{6-5}=x^1=x, so the simplified result is xx.

Takeaway: Simplify the power in the numerator before dividing, so (x2)3x5=x6x5=x\frac{({x}^{2})^{3}}{x^{5}}=\frac{x^{6}}{x^{5}}=x.

14. Example 10.53

Example 10.53

Example 10.53

Simplify: m8(m2)4.\frac{{m}^{8}}{{({m}^{2})}^{4}}.

Solution

  1. Simplify the nested power in the denominator. The power property gives (m2)4=m2⋅4=m8{({m}^{2})}^{4}=m^{2\cdot{}4}=m^8 by multiplying the inner and outer exponents.
  2. Rewrite the quotient with equal powers. The expression becomes m8m8=m8−8\frac{m^8}{m^8}=m^{8-8} by subtracting the denominator exponent.
  3. Apply the zero-exponent rule. The remaining exponent is 00, and m0=1m^0=1 for nonzero mm, so the result is 11.

Takeaway: Multiplying exponents can make the numerator and denominator identical, and m8(m2)4=m8m8=m0=1\frac{m^{8}}{({m}^{2})^{4}}=\frac{m^{8}}{m^{8}}=m^{0}=1.

15. Example 10.54

Example 10.54

Example 10.54

Simplify: (x7x3)2.{(\frac{{x}^{7}}{{x}^{3}})}^{2}.

Solution

  1. Simplify inside the parentheses first. The matching bases allow the quotient property to give x7x3=x7−3=x4\frac{x^7}{x^3}=x^{7-3}=x^4.
  2. Apply the outer square. The expression becomes (x4)2{(x^4)}^{2} after the inner quotient is simplified.
  3. Multiply the exponents. The power property gives (x4)2=x4⋅2=x8{(x^4)}^{2}=x^{4\cdot{}2}=x^8.
  4. State the result. The simplified expression is x8x^8.

Takeaway: Simplify inside the parentheses before applying the outer exponent, so (x7x3)2=(x4)2=x8(\frac{x^{7}}{x^{3}})^{2}=(x^{4})^{2}=x^{8}.

16. Example 10.55

Example 10.55

Example 10.55

Simplify: (p2q5)3.{(\frac{{p}^{2}}{{q}^{5}})}^{3}.

Solution

  1. Distribute the outer power to the fraction. The quotient to a power property gives (p2q5)3=(p2)3(q5)3{(\frac{p^2}{q^5})}^{3}=\frac{{(p^2)}^{3}}{{(q^5)}^{3}}.
  2. Multiply the exponents inside each power. The numerator becomes p2⋅3=p6p^{2\cdot{}3}=p^6, and the denominator becomes q5⋅3=q15q^{5\cdot{}3}=q^{15}.
  3. State the simplified fraction. Since the bases differ, no further cancellation is possible, so the result is p6q15\frac{p^6}{q^{15}}.

Takeaway: Raise the numerator and denominator separately when a fraction is powered, so (p2q5)3=p6q15(\frac{p^{2}}{q^{5}})^{3}=\frac{p^{6}}{q^{15}}.

17. Example 10.56

Example 10.56

Example 10.56

Simplify: (2x33y)4.{(\frac{2{x}^{3}}{3y})}^{4}.

Solution

  1. Apply the quotient to a power property. Raising the fraction to the fourth power gives (2x3)4(3y)4\frac{{(2{x}^{3})}^{4}}{{(3y)}^{4}}.
  2. Distribute the fourth power inside the fraction. The numerator and denominator become 24(x3)434y4\frac{2^4({x^3})^4}{3^4y^4}.
  3. Simplify the numerical powers. The coefficients give 24=162^4=16 and 34=813^4=81.
  4. Simplify the variable powers. Multiplying exponents gives (x3)4=x12(x^3)^4=x^{12} and y4=y4y^4=y^4, so the result is 16x1281y4\frac{16x^{12}}{81y^4}.

Takeaway: A power applies to every factor in a fraction, so (2x33y)4=16x1281y4(\frac{2x^{3}}{3y})^{4}=\frac{16x^{12}}{81y^{4}}.

18. Example 10.57

Example 10.57

Example 10.57

Simplify: (y2)3(y2)4(y5)4.\frac{{({y}^{2})}^{3}{({y}^{2})}^{4}}{{({y}^{5})}^{4}}.

Solution

  1. Simplify each nested power. The numerator exponents become 2⋅3=62\cdot{}3=6 and 2⋅4=82\cdot{}4=8, while the denominator exponent becomes 5⋅4=205\cdot{}4=20.
  2. Combine the numerator powers. The same base yy appears in both numerator factors, so adding exponents gives y6y8=y14y^6y^8=y^{14}.
  3. Apply the quotient property. The expression becomes y14y20=y14−20=y−6\frac{y^{14}}{y^{20}}=y^{14-20}=y^{-6}.
  4. Rewrite the negative exponent. Using the negative-exponent rule gives y−6=1y6y^{-6}=\frac{1}{y^6}, which is the final result.

Takeaway: Combine powers of the same base before dividing, so (y2)3(y2)4(y5)4=y14y20=1y6\frac{({y}^{2})^{3}({y}^{2})^{4}}{({y}^{5})^{4}}=\frac{y^{14}}{y^{20}}=\frac{1}{y^{6}}.

19. Divide Monomials

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.

20. Example 10.58

Example 10.58

Example 10.58

Find the quotient: 56x5÷7x2.56{x}^{5}\mathrm{÷}7{x}^{2}.

Solution

  1. Rewrite division as a fraction. The expression 56x5÷7x256{x}^{5}\div7{x}^{2} becomes 56x57x2\frac{56{x}^{5}}{7{x}^{2}}.
  2. Separate numerical and variable factors. This gives 567⋅x5x2\frac{56}{7}\cdot\frac{x^5}{x^2}.
  3. Divide the coefficients. The coefficient quotient is 567=8\frac{56}{7}=8.
  4. Subtract the exponents. The quotient property gives x5−2=x3x^{5-2}=x^3, so the complete quotient is 8x38{x}^{3}.

Takeaway: Rewrite division as a fraction, then divide coefficients and subtract exponents of like bases, giving 56x5÷7x2=8x356x^{5}\div7x^{2}=8x^{3}.

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

21. Example 10.59

Example 10.59

Example 10.59

Find the quotient: 42x2y3−7xy5.\frac{42{x}^{2}{y}^{3}}{-7x{y}^{5}}.

Solution

  1. Separate the quotient into like factors. Rewrite the expression as 42−7⋅x2x⋅y3y5\frac{42}{-7}\cdot\frac{x^2}{x}\cdot\frac{y^3}{y^5}.
  2. Divide the coefficients. The quotient 42−7\frac{42}{-7} is −6-6, so the sign is negative.
  3. Subtract each variable exponent. The powers of xx give x2−1=xx^{2-1}=x, and the powers of yy give y3−5=y−2y^{3-5}=y^{-2}.
  4. Rewrite the negative exponent. Since y−2=1y2y^{-2}=\frac{1}{y^2}, the simplified quotient is −6xy2-\frac{6x}{y^2}.

Takeaway: In a monomial quotient, divide coefficients and subtract each variable's denominator exponent from its numerator exponent, giving −6xy2-\frac{6x}{y^{2}}.

22. Example 10.60

Example 10.60

Example 10.60

Find the quotient: 24a5b348ab4.\frac{24{a}^{5}{b}^{3}}{48a{b}^{4}}.

Solution

  1. Separate the quotient into like factors. Rewrite the expression as 2448⋅a5a⋅b3b4\frac{24}{48}\cdot\frac{a^5}{a}\cdot\frac{b^3}{b^4}.
  2. Simplify the coefficient quotient. The fraction 2448\frac{24}{48} reduces to 12\frac{1}{2}.
  3. Subtract each variable exponent. The powers of aa give a5−1=a4a^{5-1}=a^4, and the powers of bb give b3−4=b−1b^{3-4}=b^{-1}.
  4. Place the negative power in the denominator. Since b−1=1bb^{-1}=\frac{1}{b}, the final quotient is a42b\frac{a^4}{2b}.

Takeaway: In a monomial quotient, divide coefficients and subtract each variable's denominator exponent from its numerator exponent, giving a42b\frac{a^{4}}{2b}.

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.

23. Example 10.61

Example 10.61

Example 10.61

Find the quotient: 14x7y1221x11y6.\frac{14{x}^{7}{y}^{12}}{21{x}^{11}{y}^{6}}.

Solution

  1. Reduce the numerical coefficients. Dividing 1414 and 2121 by their common factor 77 gives 23\frac{2}{3}.
  2. Subtract the exponent of xx. The exponent difference 7−11=−47-11=-4 gives the factor 1x4\frac{1}{x^4}.
  3. Subtract the exponent of yy. The exponent difference 12−6=612-6=6 gives the factor y6y^6.
  4. Combine the simplified factors. Putting the reciprocal and positive power together yields 2y63x4\frac{2y^6}{3x^4}.

Takeaway: Dividing coefficients and subtracting exponents independently gives 14x7y1221x11y6=2y63x4\frac{14x^{7}y^{12}}{21x^{11}y^{6}}=\frac{2y^{6}}{3x^{4}}.

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.

24. Example 10.62

Example 10.62

Example 10.62

Find the quotient: (3x3y2)(10x2y3)6x4y5.\frac{(3{x}^{3}{y}^{2})(10{x}^{2}{y}^{3})}{6{x}^{4}{y}^{5}}.

Solution

  1. Simplify the numerator first. The fraction bar groups the two monomials, so multiply their coefficients and add like exponents to get 30x5y530{x}^{5}{y}^{5}.
  2. Rewrite the whole fraction. The expression becomes 30x5y56x4y5\frac{30{x}^{5}{y}^{5}}{6{x}^{4}{y}^{5}}.
  3. Cancel the common variable powers. Dividing by 6x4y56x^4y^5 leaves the coefficient 55 and the power x5−4=xx^{5-4}=x.
  4. State the quotient. The common y5y^5 factors also cancel, so the simplified result is 5x5x.

Takeaway: The fraction bar is a grouping symbol, so simplify the numerator first: (3x3y2)(10x2y3)=30x5y5(3x^{3}y^{2})(10x^{2}y^{3})=30x^{5}y^{5}, and dividing by 6x4y56x^{4}y^{5} leaves 5x5x.

25. Section 10.4 Exercises

Section 10.4 Exercises

Section 10.4 Exercises

Simplify Expressions Using the Quotient Property of Exponents

In the following exercises, simplify.

Simplify Expressions with Zero Exponents

In the following exercises, simplify.

Simplify Expressions Using the Quotient to a Power Property

In the following exercises, simplify.

Simplify Expressions by Applying Several Properties

In the following exercises, simplify.

Divide Monomials

In the following exercises, divide the monomials.

Mixed Practice

Everyday Math

Writing Exercises

26. Self Check

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?

27. Practice 1

  1. Simplify:
  1. ⓐ  x12x9\,\frac{{x}^{12}}{{x}^{9}}
  1. ⓑ  71475\,\frac{{7}^{14}}{{7}^{5}}
  1. Simplify:
  1. ⓐ  y23y17\,\frac{{y}^{23}}{{y}^{17}}
  1. ⓑ  81587\,\frac{{8}^{15}}{{8}^{7}}
  1. Simplify:
  1. ⓐ  x8x15\,\frac{{x}^{8}}{{x}^{15}}
  1. ⓑ  12111221\,\frac{{12}^{11}}{{12}^{21}}
  1. Simplify:
  1. ⓐ  m17m26\,\frac{{m}^{17}}{{m}^{26}}
  1. ⓑ  78714\,\frac{{7}^{8}}{{7}^{14}}
  1. Simplify:
  1. ⓐ  b19b11\,\frac{{b}^{19}}{{b}^{11}}
  1. ⓑ  z5z11\,\frac{{z}^{5}}{{z}^{11}}

28. Practice 2

  1. Simplify:
  1. ⓐ  p9p17\,\frac{{p}^{9}}{{p}^{17}}
  1. ⓑ  w13w9\,\frac{{w}^{13}}{{w}^{9}}
  1. Simplify:
  1. ⓐ  170\,{17}^{0}
  1. ⓑ  m0\,{m}^{0}
  1. Simplify:
  1. ⓐ  k0\,{k}^{0}
  1. ⓑ  290\,{29}^{0}
  1. Simplify:
  1. ⓐ  (7x2y)0\,{(7{x}^{2}y)}^{0}
  1. ⓑ  7x2y0\,7{x}^{2}{y}^{0}
  1. Simplify:
  1. ⓐ  −23x2y0\,-23{x}^{2}{y}^{0}
  1. ⓑ  (−23x2y)0\,{(-23{x}^{2}y)}^{0}

29. Practice 3

  1. Simplify:
  1. ⓐ  (79)2\,{(\frac{7}{9})}^{2}
  1. ⓑ  (y8)3\,{(\frac{y}{8})}^{3}
  1. ⓒ  (pq)6\,{(\frac{p}{q})}^{6}
  1. Simplify:
  1. ⓐ  (18)2\,{(\frac{1}{8})}^{2}
  1. ⓑ  (−5m)3\,{(\frac{-5}{m})}^{3}
  1. ⓒ  (rs)4\,{(\frac{r}{s})}^{4}
  1. Simplify: (a4)5a9.\frac{{({a}^{4})}^{5}}{{a}^{9}}.
  1. Simplify: (b5)6b11.\frac{{({b}^{5})}^{6}}{{b}^{11}}.
  1. Simplify: k11(k3)3.\frac{{k}^{11}}{{({k}^{3})}^{3}}.

30. Practice 4

  1. Simplify: d23(d4)6.\frac{{d}^{23}}{{({d}^{4})}^{6}}.
  1. Simplify: (f14f8)2.{(\frac{{f}^{14}}{{f}^{8}})}^{2}.
  1. Simplify: (b6b11)2.{(\frac{{b}^{6}}{{b}^{11}})}^{2}.
  1. Simplify: (m3n8)5.{(\frac{{m}^{3}}{{n}^{8}})}^{5}.
  1. Simplify: (t10u7)2.{(\frac{{t}^{10}}{{u}^{7}})}^{2}.

31. Practice 5

  1. Simplify: (5b9c3)2.{(\frac{5b}{9{c}^{3}})}^{2}.
  1. Simplify: (4p47q5)3.{(\frac{4{p}^{4}}{7{q}^{5}})}^{3}.
  1. Simplify: (y4)4(y3)5(y7)6.\frac{{({y}^{4})}^{4}{({y}^{3})}^{5}}{{({y}^{7})}^{6}}.
  1. Simplify: (3x4)2(x3)4(x5)3.\frac{{(3{x}^{4})}^{2}{({x}^{3})}^{4}}{{({x}^{5})}^{3}}.
  1. Find the quotient: 63x8÷9x4.63{x}^{8}\mathrm{÷}9{x}^{4}.

32. Practice 6

  1. Find the quotient: 96y11÷6y8.96{y}^{11}\mathrm{÷}6{y}^{8}.
  1. Find the quotient: −84x8y37x10y2.\frac{-84{x}^{8}{y}^{3}}{7{x}^{10}{y}^{2}}.
  1. Find the quotient: −72a4b5−8a9b5.\frac{-72{a}^{4}{b}^{5}}{-8{a}^{9}{b}^{5}}.
  1. Find the quotient: 16a7b624ab8.\frac{16{a}^{7}{b}^{6}}{24a{b}^{8}}.
  1. Find the quotient: 27p4q7−45p12q.\frac{27{p}^{4}{q}^{7}}{-45{p}^{12}{q}^{}}.

33. Practice 7

  1. Find the quotient: 28x5y1449x9y12.\frac{28{x}^{5}{y}^{14}}{49{x}^{9}{y}^{12}}.
  1. Find the quotient: 30m5n1148m10n14.\frac{30{m}^{5}{n}^{11}}{48{m}^{10}{n}^{14}}.
  1. Find the quotient: (3x4y5)(8x2y5)12x5y8.\frac{(3{x}^{4}{y}^{5})(8{x}^{2}{y}^{5})}{12{x}^{5}{y}^{8}}.
  1. Find the quotient: (−6a6b9)(−8a5b8)−12a10b12.\frac{(-6{a}^{6}{b}^{9})(-8{a}^{5}{b}^{8})}{-12{a}^{10}{b}^{12}}.
  1. 4842\frac{{4}^{8}}{{4}^{2}}

34. Practice 8

  1. x12x3\frac{{x}^{12}}{{x}^{3}}
  1. r5r\frac{{r}^{5}}{r}
  1. y4y20\frac{{y}^{4}}{{y}^{20}}
  1. 1031015\frac{{10}^{3}}{{10}^{15}}
  1. aa9\frac{a}{{a}^{9}}

35. Practice 9

  1. −70-{7}^{0}
  1. 1. ⓐ  (10p)0\,{(10p)}^{0}
  1. ⓑ  10p0\,10{p}^{0}
  1. 1. ⓐ  (−27x5y)0\,{(-27{x}^{5}y)}^{0}
  1. ⓑ  −27x5y0\,-27{x}^{5}{y}^{0}
  1. 1. ⓐ  150\,{15}^{0}
  1. ⓑ  151\,{15}^{1}
  1. (32)5{(\frac{3}{2})}^{5}

36. Practice 10

  1. (m6)3{(\frac{m}{6})}^{3}
  1. (xy)10{(\frac{x}{y})}^{10}
  1. (a3b)2{(\frac{a}{3b})}^{2}
  1. (x2)4x5\frac{{({x}^{2})}^{4}}{{x}^{5}}
  1. (u3)4u10\frac{{({u}^{3})}^{4}}{{u}^{10}}

37. Practice 11

  1. y8(y5)2\frac{{y}^{8}}{{({y}^{5})}^{2}}
  1. (x2x8)3{(\frac{{x}^{2}}{{x}^{8}})}^{3}
  1. (a4 ⋅ a6a3)2{(\frac{{a}^{4}\,\cdot\,{a}^{6}}{{a}^{3}})}^{2}
  1. (y3)5(y4)3\frac{{({y}^{3})}^{5}}{{({y}^{4})}^{3}}
  1. (x3)6(x4)7\frac{{({x}^{3})}^{6}}{{({x}^{4})}^{7}}

38. Practice 12

  1. (2r35s)4{(\frac{2{r}^{3}}{5s})}^{4}
  1. (r2)5 (r4)2(r3)7\frac{{({r}^{2})}^{5}\,{({r}^{4})}^{2}}{{({r}^{3})}^{7}}
  1. (3x4)3 (2x3)2(6x5)2\frac{{(3{x}^{4})}^{3}\,{(2{x}^{3})}^{2}}{{(6{x}^{5})}^{2}}
  1. 48b8÷6b248{b}^{8}\mathrm{÷}6{b}^{2}
  1. 36x3÷(−2x9)36{x}^{3}\mathrm{÷}(-2{x}^{9})

39. Practice 13

  1. 18x39x2\frac{18{x}^{3}}{9{x}^{2}}
  1. −35x7−42x13\frac{-35{x}^{7}}{-42{x}^{13}}
  1. 18r5s3r3s9\frac{18{r}^{5}s}{3{r}^{3}{s}^{9}}
  1. 8mn1064mn4\frac{8m{n}^{10}}{64m{n}^{4}}
  1. −12x4y915x6y3\frac{-12{x}^{4}{y}^{9}}{15{x}^{6}{y}^{3}}

40. Practice 14

  1. 64x5y9z748x7y12z6\frac{64{x}^{5}{y}^{9}{z}^{7}}{48{x}^{7}{y}^{12}{z}^{6}}
  1. (6m2n)(5m4n3)3m10n2\frac{(6{m}^{2}n)(5{m}^{4}{n}^{3})}{3{m}^{10}{n}^{2}}
  1. (4u5v4)(15u8v)(12u3v)(u6v)\frac{(4{u}^{5}{v}^{4})(15{u}^{8}v)}{(12{u}^{3}v)({u}^{6}v)}
  1. 1. ⓐ  15n10+3n10\,15{n}^{10}+3{n}^{10}
  1. ⓑ  15n10−3n10\,15{n}^{10}-3{n}^{10}
  1. ⓒ  15n10⋅3n10\,15{n}^{10}\cdot{}3{n}^{10}
  1. ⓓ  15n10÷3n10\,15{n}^{10}\mathrm{÷}3{n}^{10}
  1. 1. ⓐ  q5⋅q3\,{q}^{5}\cdot{q}^{3}
  1. ⓑ  (q5)3\,{({q}^{5})}^{3}

41. Practice 15

  1. 1. ⓐ  z6z5\,\frac{{z}^{6}}{{z}^{5}}
  1. ⓑ  z5z6\,\frac{{z}^{5}}{{z}^{6}}
  1. (4y)(12y7)÷8y2(4y)(12{y}^{7})\mathrm{÷}8{y}^{2}
  1. 32c114c5+42c96c3\frac{32{c}^{11}}{4{c}^{5}}+\frac{42{c}^{9}}{6{c}^{3}}
  1. 48x66x4−35x97x7\frac{48{x}^{6}}{6{x}^{4}}-\frac{35{x}^{9}}{7{x}^{7}}
  1. 56y4z57y3z3−45y2z25y\frac{56{y}^{4}{z}^{5}}{7{y}^{3}{z}^{3}}-\frac{45{y}^{2}{z}^{2}}{5y}

42. Practice 16

  1. Memory One megabyte is approximately 106{10}^{6} bytes. One terabyte is approximately 1012{10}^{12} bytes. How many megabytes are in one terabyte?
  1. Mai simplifies the quotient y3y\frac{{y}^{3}}{y} by writing y3y=3.\frac{{y}^{3}}{y}=3. What is wrong with her reasoning?
  1. Roxie thinks n0{n}^{0} simplifies to 0.0. What would you say to convince Roxie she is wrong?

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