Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 3 - Review - Exercises - Page 322: 97

Answer

$(-∞, -2) U (1, 2) $

Work Step by Step

$\frac{5}{x^3 - x^2 - 4x + 4} < 0$ Find the zeros of the expressions in the numerator AND the denominator $\frac{5}{x^2 (x - 1) - 4 (x-1)} < 0$ $\frac{5}{(x^2 - 4) (x-1)} < 0$ $\frac{5}{(x+2) (x-1) (x-2)} < 0$ x = -2, 1, 2 Test numbers in between those zero values to determine if the function is negative or positive (-∞, -2) $\frac{(+)}{(-)(-)(-)} = (-)$ (-2, 1) $\frac{(+)}{(+)(-)(-)} = (+)$ (1, 2) $\frac{(+)}{(+)(+)(-)} = (-)$ (2, ∞) $\frac{(+)}{(+)(+)(+)} = (+)$ Thus the solution is $(-∞, -2) U (1, 2) $
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