Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Published by Pearson
ISBN 10: 0-32184-874-8
ISBN 13: 978-0-32184-874-1

Chapter 6 - Rational Expressions and Equations - 6.1 Rational Expressions - 6.1 Exercise Set - Page 380: 69


The numerator evaluates to zero.

Work Step by Step

In this case, we see that though he simplifies incorrectly in the denominator, the numerator still has a zero at $x=1$. Because of this, the function evaluates to 0 both times he plugs this in even though the two expressions are not the same, showing why this check is not foolproof.
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