Intermediate Algebra (12th Edition)

Published by Pearson
ISBN 10: 0321969359
ISBN 13: 978-0-32196-935-4

Chapter 8 - Section 8. - Equations Quadratic in Form - 8.3 Exercises - Page 528: 16

Answer

$\left\{0,\dfrac{59}{13}\right\}$

Work Step by Step

Multiplying by the $LCD= 15(3-p)(5-p) ,$ the given equation $ \dfrac{4}{3-p}+\dfrac{2}{5-p}=\dfrac{26}{15} ,$ is equivalent to \begin{align*}\require{cancel} 15(3-p)(5-p)\left(\dfrac{4}{3-p}+\dfrac{2}{5-p}\right)&=\left(\dfrac{26}{15}\right)15(3-p)(5-p) \\\\ 15(5-p)(4)+15(3-p)(2)&=26(3-p)(5-p) \\ 300-60p+90-30p&=26(15-8p+p^2) \\ 390-90p&=390-208p+26p^2 \\ 0&=26p^2+(-208p+90p)+(390-390) \\ 0&=26p^2-118p \\\\ \dfrac{0}{2}&=\dfrac{26p^2-118p}{2} \\\\ 0&=13p^2-59p \\ 13p^2-59p&=0 .\end{align*} Factoring the $GCF=p,$ the equation above is equivalent to \begin{align*} p(13p-59)&=0 .\end{align*} Equating each factor to zero (Zero Product Property) and solving for the variable, then \begin{array}{l|r} p=0 & 13p-59=0 \\ & 13p=59 \\\\ & p=\dfrac{59}{13} .\end{array} Checking the solutions by substitution in the given equation results to \begin{array}{l|r} \text{If }p=0: & \text{If }p=\dfrac{59}{13}: \\\\ \dfrac{4}{3-0}+\dfrac{2}{5-0}\overset{?}=\dfrac{26}{15} & \dfrac{4}{3-\frac{59}{13}}+\dfrac{2}{5-\frac{59}{13}}\overset{?}=\dfrac{26}{15} \\\\ \dfrac{4}{3}+\dfrac{2}{5}\overset{?}=\dfrac{26}{15} & \dfrac{4}{\frac{39}{13}-\frac{59}{13}}+\dfrac{2}{\frac{65}{13}-\frac{59}{13}}\overset{?}=\dfrac{26}{15} \\\\ \dfrac{4}{3}\cdot\dfrac{5}{5}+\dfrac{2}{5}\cdot\dfrac{3}{3}\overset{?}=\dfrac{26}{15} & \dfrac{4}{-\frac{20}{13}}+\dfrac{2}{\frac{6}{13}}\overset{?}=\dfrac{26}{15} \\\\ \dfrac{20}{15}+\dfrac{6}{15}\overset{?}=\dfrac{26}{15} & 4\cdot\left(-\dfrac{13}{20}\right)+2\cdot\dfrac{13}{6}\overset{?}=\dfrac{26}{15} \\\\ \dfrac{26}{15}\overset{\checkmark}=\dfrac{26}{15} & -\dfrac{13}{5}+\dfrac{13}{3}\overset{?}=\dfrac{26}{15} \\\\& -\dfrac{13}{5}\cdot\dfrac{3}{3}+\dfrac{13}{3}\cdot\dfrac{5}{5}\overset{?}=\dfrac{26}{15} \\\\& -\dfrac{39}{15}+\dfrac{65}{15}\overset{?}=\dfrac{26}{15} \\\\& \dfrac{26}{15}\overset{\checkmark}=\dfrac{26}{15} .\end{array} Since both solutions satisfy the given equation, then the solution set of the equation $ \dfrac{4}{3-p}+\dfrac{2}{5-p}=\dfrac{26}{15} $ is $\left\{0,\dfrac{59}{13}\right\}$.
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