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8.2 Multiply and Divide Rational Expressions

Factoring both parts of every fraction before any canceling, and rewriting a division as multiplication by the reciprocal.

Elementary Algebra 2e, 8.2 Multiply and Divide Rational Expressions

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65 exercises

8.2 Exercise 1

If you miss a problem, go back to the section listed and review the material.

Multiply: 1415·635.\frac{14}{15} \cdot \frac{6}{35} .
If you missed this problem, review the reference.

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8.2 Exercise 2

Divide: 1415÷635.\frac{14}{15} \div \frac{6}{35} .
If you missed this problem, review the reference.

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8.2 Exercise 3

Factor completely: 2x2−98.2 x^{2} - 98 .
If you missed this problem, review the reference.

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8.2 Exercise 4

Factor completely: 10n3+10.10 n^{3} + 10 .
If you missed this problem, review the reference.

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8.2 Exercise 5

Factor completely: 10p2−25pq−15q2.10 p^{2} - 25 p q - 15 q^{2} .
If you missed this problem, review the reference.

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8.2 Exercise 7

Mulitply: 610·1512.\frac{6}{10} \cdot \frac{15}{12} .

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8.2 Exercise 8

Mulitply: 2015·68.\frac{20}{15} \cdot \frac{6}{8} .

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8.2 Exercise 10

Mulitply: 3pqq2·5p2q6pq.\frac{3 p q}{q^{2}} \cdot \frac{5 p^{2} q}{6 p q} .

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8.2 Exercise 11

Mulitply: 6x3y7x2·2xy3x2y.\frac{6 x^{3} y}{7 x^{2}} \cdot \frac{2 x y^{3}}{x^{2} y} .

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8.2 Exercise 13

Mulitply: 5xx2+5x+6·x2−410x.\frac{5 x}{x^{2} + 5 x + 6} \cdot \frac{x^{2} - 4}{10 x} .

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8.2 Exercise 14

Mulitply: 9x2x2+11x+30·x2−363x2.\frac{9 x^{2}}{x^{2} + 11 x + 30} \cdot \frac{x^{2} - 36}{3 x^{2}} .

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8.2 Exercise 15

Multiply: n2−7nn2+2n+1·n+12n.\frac{n^{2} - 7 n}{n^{2} + 2 n + 1} \cdot \frac{n + 1}{2 n} .

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8.2 Exercise 16

Multiply: x2−25x2−3x−10·x+2x.\frac{x^{2} - 25}{x^{2} - 3 x - 10} \cdot \frac{x + 2}{x} .

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8.2 Exercise 17

Multiply: x2−4xx2+5x+6·x+2x.\frac{x^{2} - 4 x}{x^{2} + 5 x + 6} \cdot \frac{x + 2}{x} .

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8.2 Exercise 18

Multiply: 16−4x2x−12·x2−5x−6x2−16.\frac{16 - 4 x}{2 x - 12} \cdot \frac{x^{2} - 5 x - 6}{x^{2} - 16} .

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8.2 Exercise 19

Multiply: 12x−6x2x2+8x·x2+11x+24x2−4.\frac{12 x - 6 x^{2}}{x^{2} + 8 x} \cdot \frac{x^{2} + 11 x + 24}{x^{2} - 4} .

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8.2 Exercise 20

Multiply: 9v−3v29v+36·v2+7v+12v2−9.\frac{9 v - 3 v^{2}}{9 v + 36} \cdot \frac{v^{2} + 7 v + 12}{v^{2} - 9} .

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8.2 Exercise 22

Multiply: 3a−21a2−9a+14·a2−43a+6.\frac{3 a - 21}{a^{2} - 9 a + 14} \cdot \frac{a^{2} - 4}{3 a + 6} .

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8.2 Exercise 23

Multiply: b2−bb2+9b−10·b2−100b2−10b.\frac{b^{2} - b}{b^{2} + 9 b - 10} \cdot \frac{b^{2} - 100}{b^{2} - 10 b} .

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8.2 Exercise 25

Divide: c+35−c÷c2−9c−5.\frac{c + 3}{5 - c} \div \frac{c^{2} - 9}{c - 5} .

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8.2 Exercise 26

Divide: 2−dd−4÷4−d24−d.\frac{2 - d}{d - 4} \div \frac{4 - d^{2}}{4 - d} .

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8.2 Exercise 28

Divide: 2m2m2−8m÷8m2+24mm2+m−6.\frac{2 m^{2}}{m^{2} - 8 m} \div \frac{8 m^{2} + 24 m}{m^{2} + m - 6} .

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8.2 Exercise 29

Divide: 15n23n2+33n÷5n−5n2+9n−22.\frac{15 n^{2}}{3 n^{2} + 33 n} \div \frac{5 n - 5}{n^{2} + 9 n - 22} .

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8.2 Exercise 30

Divide: 2x2+5x−12x2−16÷2x2−13x+15x2−8x+16.\frac{2 x^{2} + 5 x - 12}{x^{2} - 16} \div \frac{2 x^{2} - 13 x + 15}{x^{2} - 8 x + 16} .

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8.2 Exercise 31

Divide: 3a2−8a−3a2−25÷3a2−14a−5a2+10a+25.\frac{3 a^{2} - 8 a - 3}{a^{2} - 25} \div \frac{3 a^{2} - 14 a - 5}{a^{2} + 10 a + 25} .

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8.2 Exercise 32

Divide: 4b2+7b−21−b2÷4b2+15b−4b2−2b+1.\frac{4 b^{2} + 7 b - 2}{1 - b^{2}} \div \frac{4 b^{2} + 15 b - 4}{b^{2} - 2 b + 1} .

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8.2 Exercise 33

Divide: p3+q32p2+2pq+2q2÷p2−q26.\frac{p^{3} + q^{3}}{2 p^{2} + 2 p q + 2 q^{2}} \div \frac{p^{2} - q^{2}}{6} .

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8.2 Exercise 34

Divide: x3−83x2−6x+12÷x2−46.\frac{x^{3} - 8}{3 x^{2} - 6 x + 12} \div \frac{x^{2} - 4}{6} .

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8.2 Exercise 35

Divide: 2z2z2−1÷z3−z2+zz3−1.\frac{2 z^{2}}{z^{2} - 1} \div \frac{z^{3} - z^{2} + z}{z^{3} - 1} .

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8.2 Exercise 36

Divide: a2−b23ab÷(a2+2ab+b2).\frac{a^{2} - b^{2}}{3 a b} \div \left(a^{2} + 2 a b + b^{2}\right) .

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8.2 Exercise 37

Divide: 2x2−14x−164÷(x2+2x+1).\frac{2 x^{2} - 14 x - 16}{4} \div \left(x^{2} + 2 x + 1\right) .

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8.2 Exercise 38

Divide: y2−6y+8y2−4y÷(3y2−12y).\frac{y^{2} - 6 y + 8}{y^{2} - 4 y} \div \left(3 y^{2} - 12 y\right) .

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8.2 Exercise 39

Divide: 6x2−7x+24x−82x2−7x+3x2−5x+6.\frac{\frac{6 x^{2} - 7 x + 2}{4 x - 8}}{\frac{2 x^{2} - 7 x + 3}{x^{2} - 5 x + 6}} .

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8.2 Exercise 40

Divide: 3x2+7x+24x+243x2−14x−5x2+x−30.\frac{\frac{3 x^{2} + 7 x + 2}{4 x + 24}}{\frac{3 x^{2} - 14 x - 5}{x^{2} + x - 30}} .

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8.2 Exercise 41

Divide: y2−362y2+11y−62y2−2y−608y−4.\frac{\frac{y^{2} - 36}{2 y^{2} + 11 y - 6}}{\frac{2 y^{2} - 2 y - 60}{8 y - 4}} .

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8.2 Exercise 43

Divide: 4m+43m−15·m2−3m−10m2−4m−32÷12m−366m−48.\frac{4 m + 4}{3 m - 15} \cdot \frac{m^{2} - 3 m - 10}{m^{2} - 4 m - 32} \div \frac{12 m - 36}{6 m - 48} .

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8.2 Exercise 44

Divide: 2n2+10nn−1÷n2+10n+24n2+8n−9·n+48n2+12n.\frac{2 n^{2} + 10 n}{n - 1} \div \frac{n^{2} + 10 n + 24}{n^{2} + 8 n - 9} \cdot \frac{n + 4}{8 n^{2} + 12 n} .

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8.2 Exercise 45

Multiply.

1216·410\frac{12}{16} \cdot \frac{4}{10}

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8.2 Exercise 47

Multiply.

1810·430\frac{18}{10} \cdot \frac{4}{30}

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8.2 Exercise 49

Multiply.

5x2y412xy3·6x220y2\frac{5 x^{2} y^{4}}{12 x y^{3}} \cdot \frac{6 x^{2}}{20 y^{2}}

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8.2 Exercise 51

Multiply.

12a3bb2·2ab29b3\frac{12 a^{3} b}{b^{2}} \cdot \frac{2 a b^{2}}{9 b^{3}}

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8.2 Exercise 53

Multiply.

5p2p2−5p−36·p2−1610p\frac{5 p^{2}}{p^{2} - 5 p - 36} \cdot \frac{p^{2} - 16}{10 p}

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8.2 Exercise 55

Multiply.

4rr2−3r−10·r2−258r2\frac{4 r}{r^{2} - 3 r - 10} \cdot \frac{r^{2} - 25}{8 r^{2}}

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8.2 Exercise 57

Multiply.

x2−7xx2+6x+9·x+34x\frac{x^{2} - 7 x}{x^{2} + 6 x + 9} \cdot \frac{x + 3}{4 x}

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8.2 Exercise 59

Multiply.

z2+3zz2−3z−4·z−4z2\frac{z^{2} + 3 z}{z^{2} - 3 z - 4} \cdot \frac{z - 4}{z^{2}}

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8.2 Exercise 61

Multiply.

28−4b3b−3·b2+8b−9b2−49\frac{28 - 4 b}{3 b - 3} \cdot \frac{b^{2} + 8 b - 9}{b^{2} - 49}

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8.2 Exercise 63

Multiply.

35d−7d2d2+7d·d2+12d+35d2−25\frac{35 d - 7 d^{2}}{d^{2} + 7 d} \cdot \frac{d^{2} + 12 d + 35}{d^{2} - 25}

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8.2 Exercise 65

Multiply.

4n+20n2+n−20·n2−164n+16\frac{4 n + 20}{n^{2} + n - 20} \cdot \frac{n^{2} - 16}{4 n + 16}

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8.2 Exercise 67

Multiply.

q2−2qq2+6q−16·q2−64q2−8q\frac{q^{2} - 2 q}{q^{2} + 6 q - 16} \cdot \frac{q^{2} - 64}{q^{2} - 8 q}

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8.2 Exercise 69

Divide.

t−63−t÷t−5t2−9\frac{t - 6}{3 - t} \div \frac{t - 5}{t^{2} - 9}

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8.2 Exercise 71

Divide.

10+ww−8÷100−w28−w\frac{10 + w}{w - 8} \div \frac{100 - w^{2}}{8 - w}

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8.2 Exercise 73

Divide.

27y23y−21÷3y2+18y2+13y+42\frac{27 y^{2}}{3 y - 21} \div \frac{3 y^{2} + 18}{y^{2} + 13 y + 42}

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8.2 Exercise 75

Divide.

16a24a+36÷4a2−24aa2+4a−45\frac{16 a^{2}}{4 a + 36} \div \frac{4 a^{2} - 24 a}{a^{2} + 4 a - 45}

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8.2 Exercise 77

Divide.

5c2+9c−2c2−4÷5c2−16c+3c2+4c+4\frac{5 c^{2} + 9 c - 2}{c^{2} - 4} \div \frac{5 c^{2} - 16 c + 3}{c^{2} + 4 c + 4}

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8.2 Exercise 79

Divide.

6m2−11m−29−m2÷6m2+25m+4m2−6m+9\frac{6 m^{2} - 11 m - 2}{9 - m^{2}} \div \frac{6 m^{2} + 25 m + 4}{m^{2} - 6 m + 9}

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8.2 Exercise 81

Divide.

3s2s2−16÷s3+4s2+16ss3−64\frac{3 s^{2}}{s^{2} - 16} \div \frac{s^{3} + 4 s^{2} + 16 s}{s^{3} - 64}

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8.2 Exercise 83

Divide.

p3+q33p2+3pq+3q2÷p2−q212\frac{p^{3} + q^{3}}{3 p^{2} + 3 p q + 3 q^{2}} \div \frac{p^{2} - q^{2}}{12}

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8.2 Exercise 85

Divide.

t2−92t÷(t2−6t+9)\frac{t^{2} - 9}{2 t} \div \left(t^{2} - 6 t + 9\right)

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8.2 Exercise 87

Divide.

2y2−10yz−48z22y−1÷(4y2−32yz)\frac{2 y^{2} - 10 y z - 48 z^{2}}{2 y - 1} \div \left(4 y^{2} - 32 y z\right)

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8.2 Exercise 89

Divide.

2a2−a−215a+20a2+7a+12a2+8a+16\frac{\frac{2 a^{2} - a - 21}{5 a + 20}}{\frac{a^{2} + 7 a + 12}{a^{2} + 8 a + 16}}

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8.2 Exercise 91

Divide.

12c2−122c2−3c+14c+46c2−13c+5\frac{\frac{12 c^{2} - 12}{2 c^{2} - 3 c + 1}}{\frac{4 c + 4}{6 c^{2} - 13 c + 5}}

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8.2 Exercise 93

Divide.

10m2+80m3m−9·m2+4m−21m2−9m+20\frac{10 m^{2} + 80 m}{3 m - 9} \cdot \frac{m^{2} + 4 m - 21}{m^{2} - 9 m + 20}
÷5m2+10m2m−10\div \frac{5 m^{2} + 10 m}{2 m - 10}

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8.2 Exercise 95

Divide.

12p2+3pp+3÷p2+2p−63p2−p−12\frac{12 p^{2} + 3 p}{p + 3} \div \frac{p^{2} + 2 p - 63}{p^{2} - p - 12}
·p−79p3−9p2\cdot \frac{p - 7}{9 p^{3} - 9 p^{2}}

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8.2 Exercise 97

Probability The director of large company is interviewing applicants for two identical jobs. If w=w = the number of women applicants and m=m = the number of men applicants, then the probability that two women are selected for the jobs is ww+m·w−1w+m−1.\frac{w}{w + m} \cdot \frac{w - 1}{w + m - 1} .

  1. ⓐ Simplify the probability by multiplying the two rational expressions.
  2. ⓑ Find the probability that two women are selected when w=5w = 5 and m=10m = 10.
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8.2 Exercise 99

  1. ⓐ Multiply 74·910\frac{7}{4} \cdot \frac{9}{10} and explain all your steps.
  2. ⓑ Multiply nn−3·9n+3\frac{n}{n - 3} \cdot \frac{9}{n + 3} and explain all your steps.
  3. ⓒ Evaluate your answer to part (b) when n=7.n = 7 . Did you get the same answer you got in part (a)? Why or why not?
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Adapted from Elementary Algebra 2e © 2020 Rice University. Licensed under CC BY 4.0. Source: Elementary Algebra 2e. Imported at revision 77a933c.