Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

Published by Pearson
ISBN 10: 0-32193-104-1
ISBN 13: 978-0-32193-104-7

Chapter 13 - A Preview of Calculus: The Limit, Derivative, and Integral of a Function - Section 13.3 One-sided Limits; Continuous Functions - 13.3 Assess Your Understanding - Page 910: 75

Answer

not continuous at $x=-1$ or $x=1$.

Work Step by Step

1. See graph for $R(x)=\frac{x^2+x}{x^2-1}=\frac{x(x+1)}{(x+1)(x-1)}=\frac{x}{x-1}, x\ne-1$ with V.A. $x=1$, H.A. $y=1$ and a hole at $(-1, \frac{1}{2})$. 2. Although $\lim_{x\to-1}R(x)=\frac{1}{2}$, the function is not continuous at $x=-1$ because of the hole. 3. We have $\lim_{x\to 1^-}R(x)=-\infty$ and $\lim_{x\to 1^+}R(x)=\infty$, thus the function is not continuous at $x=1$.
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