Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 2 - Section 2.6 - Rational Functions and Their Graphs - Exercise Set - Page 399: 66

Answer

Graph the function as:

Work Step by Step

Step 1: Substitute $x=-x$ $\begin{align} & f\left( x \right)=\frac{-2}{{{x}^{2}}-1} \\ & f\left( -x \right)=\frac{-2}{{{\left( -x \right)}^{2}}-1} \\ & =\frac{-2}{{{x}^{2}}-1} \\ & =f\left( x \right) \end{align}$ And, $\begin{align} & -f\left( x \right)=-\left( \frac{-2}{{{x}^{2}}-1} \right) \\ & =\frac{2}{{{x}^{2}}-1} \\ & \ne f\left( -x \right) \end{align}$ Therefore, the graph of the function is symmetric about the $y$-axis but not about the origin. Step 2: To calculate the x intercepts equate $f\left( x \right)=0$. $-\frac{2}{{{x}^{2}}-1}=0$ , Which is not true for any value of x. Thus, there are no x-intercepts. Step 3: To calculate the y intercepts, evaluate $f\left( 0 \right)$. $\begin{align} & f\left( 0 \right)=\frac{-2}{\left( 0 \right)-1} \\ & f\left( 0 \right)=2 \\ \end{align}$ Step 4: Since the degree of the numerator is less than the denominator, there is no horizontal asymptote. Step 5: For the vertical asymptote, equate the denominator to 0. $\begin{align} & {{x}^{2}}-1=0 \\ & x=\pm 1 \end{align}$
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