Introductory Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-805-X
ISBN 13: 978-0-13417-805-9

Chapter 7 - Section 7.1 - Rational Expressions and Their Simplification - Exercise Set - Page 491: 18


The expression is undefined for $y=-7$ and for $y=7.$

Work Step by Step

Rational expressions indicate division and division by zero is undefined. We must exclude any value or values of the variable that make a denominator zero. The denominator, $y^{2}-49$ yields zero for $y^{2}-49=0$ $y^{2}-7^{2}=0$ $(y+7)(y-7)=0,$ for $y=-7$ and for $y=7.$ The expression is undefined for $y=-7$ and for $y=7.$
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