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 - Chapter Review - Review Exercises - Page 115: 37

Answer

$\text{(a)}$ $(-2,\infty)$. $\text{(b)}$ $x$-intercetp $=0$; $y$-intercept $=0$ $\text{(c)}$ See graph below. $\text{(d)}$ $(-6,\infty)$. $\text{(e)}$ not continuous

Work Step by Step

Use the given piece-wise function, we can find: $\text{(a)}$ The $x$-values of the function are the real numbers greater than $-2$. Hence, the domain $(-2,\infty)$. $\text{(b)}$ For $x$-intercept, let $f(x)=0$ then solve for $x$. $0=3x \longrightarrow x=0$, while $0=x+1\longrightarrow x=-1$. Note that $f(0)=0$ and $f(-1) = -3$. Thus, the $x$-intercept is $0$. For $y$-intercept, let $x=0$ then solve for $y$. Note that $f(0)=3(0)=0$, Thus, the $y$-intercept is $0$. $\text{(c)}$ Graph each part/piece of the function.. For $f(x)=3x, -2\le x \le 1$: When $x=-2$, $f(-2)= 3(-2)=-6$. However, since $-2$ is not part of the domain, then plot the point $(-2, -6)$using a hollow dot. When $x=1$, $f(1)=3(1)=3$. Thus, the graph contains $(1, 3)$. Plot the points $(-3, -6)$ and $(1, 3)$ then connect the points using a solid line. For $f(x)=x+1, x> 1$: When $x=1$, $f(1)=1+1=2$. However, since $1$ is not part of the domain, then plot the point $(1, 2)$using a hollow dot. When $x=5$, $f(5)=5+1=6$. Thus, the graph contains $(5, 6)$. Plot the points $(1, 2)$ and $(5, 6)$ then connect them using a line, and finally, extend the line by putting an arrowhead going upward to the right. Refer to the graph below. $\text{(d)}$ The graph shows that the value of $y$ is any real number greater then $-6$. Hence, the range is $(-6,\infty)$. $\text{(e)}$ The function is not continuous on its domain (discontinuous at $x=1$).
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