Precalculus (6th Edition) Blitzer

Published by Pearson
ISBN 10: 0-13446-914-3
ISBN 13: 978-0-13446-914-0

Chapter 2 - Section 2.7 - Polynomial and Rational Inequalities - Exercise Set - Page 413: 51

Answer

$(-∞, 0) ∪ (3, ∞)$

Work Step by Step

Consider the Rational Inequality as follows: $\frac{x}{x-3}\gt0$ Here are the steps required for Solving Rational Inequalities: Step 1: One side must be zero and the other side can have only one fraction, so we simplify the fractions if there is more than one fraction. $\frac{x}{x-3}\gt0$ Step 2: Critical or Key Values are first evaluated. In order to do this, set the numerator and denominator of the fraction equal to zero and solve. $x = 0$ This implies $x =0$ and $x-3=0$ This implies $ x =3$ These solutions are used as boundary points on a number line. Step 3: Locate the boundary points on a number line and divide the number line into intervals. The boundary points divide the number line into three intervals: $(-∞, 0), (0,3), (3, ∞)$ Step 4. Now, one test value within each interval is chosen and $f$ is evaluated at that number. Intervals: $(-∞, 0), (0,3), (3, ∞)$ Test value: $-1$ $2$ $4$ Sign Change: Positive Negative Positive $f (x) > 0?$: T F T Step 5: Write the solution set, selecting the interval or intervals that satisfy the given inequality. We are interested in solving $f (x) > 0$. Based on our work done in Step 4, we see that $f (x) > 0$ for all x in $(-∞, 0) or (3, ∞)$. Conclusion: Thus, the interval notation of the given inequality is $(-∞, 0) ∪ (3, ∞)$ and the graph of the solution set on a number line is shown as follows:
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