Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 6 - Section 6.1 - Rational Expressions and Functions; Multiplying and Dividing - Exercise Set - Page 415: 103

Answer

$\left(\dfrac{f}{g}\right)(x)=-x-2$ Domain: $(-\infty,-2)\cup(2,0.5)\cup(0.5,\infty)$

Work Step by Step

We are given the functions: $$\begin{align*} f(x)&=\dfrac{(x+2)^2}{1-2x}\\ g(x)&=\dfrac{x+2}{2x-1}. \end{align*}$$ Determine $\dfrac{f}{g}$: $$\begin{align*} \left(\dfrac{f}{g}\right)(x)&=\dfrac{f(x)}{g(x)}\\ &=\dfrac{\dfrac{(x+2)^2}{1-2x}}{\dfrac{x+2}{2x-1}}\quad&&\text{Substitute the expressions of }f\text{ and }g\\ &=-\dfrac{(x+2)^2}{2x-1}\cdot \dfrac{2x-1}{x+2}\quad&&\text{Invert the divisor and multiply.}\\ &=-x-2\quad&&\text{Divide numerators and denominators}\\ &\quad&&\text{ by common factors.} \end{align*}$$ The domain of the function $\dfrac{f}{g}$ is obtained solving the following system of inequalities: $$\begin{cases} 1-2x&\not=0\\ 2x-1&\not=0\\ x+2&\not=0. \end{cases}\\ \begin{cases} x&\not=0.5\\ x&\not=0.5\\ x&\not=-2. \end{cases}$$ The solution is $(-\infty,-2)\cup(2,0.5)\cup(0.5,\infty)$. $\left(\dfrac{f}{g}\right)(x)=-x-2$ Domain: $(-\infty,-2)\cup(2,0.5)\cup(0.5,\infty)$
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