Precalculus (10th Edition)

Published by Pearson
ISBN 10: 0-32197-907-9
ISBN 13: 978-0-32197-907-0

Chapter 2 - Functions and Their Graphs - 2.1 Functions - 2.1 Assess Your Understanding - Page 57: 46

Answer

a) $f(0)=-\frac{1}{4}$ (b). $f(1)=0$ (c). $f(-1)=0$ (d) $f(-x)=\frac{x^2-1}{4-x}$ (e) $-f(x)=-\frac{x^2-1}{x+4}$ or $-f(x)=\frac{1-x^2}{x+4}$ (f) $f(x+1)=\frac{x^2+2x}{x+5}$ (g) $f(2x)=\frac{4x^2-1}{2x+4}$ (h) $f(x+h)=\frac{x^2+2xh+h^2-1}{x+h+4}$

Work Step by Step

Given $f(x)=\frac{x^2-1}{x+4}$ a) To Evaluate $f(0)$ in the given function, substitute $0$ in the place of $x$. $f(0)=\frac{0^2-1}{0+4}=\frac{-1}{4}=-\frac{1}{4}$ (b). To Evaluate $f(1)$ in the given function, substitute $1$ in the place of $x$. $f(1)=\frac{1^2-1}{1+4}=\frac{1-1}{1+4}=-\frac{0}{5}=0$ (c). To Evaluate $f(−1)$ in the given function, substitute $−1$ in the place of $x$. $f(-1)=\frac{(-1)^2-1}{-1+4}=\frac{1-1}{-1+4}=\frac{0}{3}=0$ (d) To Evaluate $f(−x)$ in the given function, substitute $−x$ in the place of $x$. $f(-x)= \frac{(-x)^2-1}{-x+4}=\frac{x^2-1}{4-x}$ (e) To Evaluate $−f(x)$ in the given function, $-f(x)=-\frac{x^2-1}{x+4}$ This can also be written as $-f(x)=\frac{1-x^2}{x+4}$ (f) To Evaluate $f(x+1)$ in the given function, substitute $x+1$ in the place of $x$. $f(x+1)=\frac{(x+1)^2-1}{(x+1)+4}=\frac{x^2+2x+1-1}{x+1+4}=\frac{x^2+2x}{x+5}$ (g) To Evaluate $f(2x)$ in the given function, substitute $2x$ in the place of $x$. $f(2x)=\frac{(2x)^2-1}{2x+4}=\frac{4x^2-1}{2x+4}$ (h) To Evaluate $f(x+h)$ in the given function, substitute $x+h$ in the place of $x$. $f(x+h)=\frac{(x+h)^2-1}{(x+h)+4}=\frac{x^2+2xh+h^2-1}{x+h+4}$
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