## Introductory Algebra for College Students (7th Edition)

Published by Pearson

# Chapter 7 - Section 7.1 - Rational Expressions and Their Simplification - Exercise Set - Page 491: 19

#### Answer

This expression is defined for all real numbers.

#### Work Step by Step

A rational expression is undefined when the value of its denominator is zero. Write and solve an expression where the denominator is zero. $x^2+1=0$ Use the addition property of equality to solve both equations for y. $x^2+1-1=0-1$ Simplify. $x^2=-1$ Since the square of a number can never be negative, this denominator can never be negative. This expression is defined for all real numbers.

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