Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 3 - Section 3.7 - Polynomial and Rational Inequalities - 3.7 Exercises - Page 316: 19

Answer

$(-7, -5/2] U (5, ∞) $

Work Step by Step

$\frac{2x+5}{x^2 +2x - 35} \geq 0$ Find the zeros of the expressions in the numerator AND the denominator $2x + 5 = 0$; $(x+7)(x-5) = 0$ $x = -5/2, -7, 5$ Test numbers in between those zero values to determine if the function is negative or positive (-∞, -7) $\frac{(-)}{(-)(-)} = (-)$ (-7, -5/2] $\frac{(-)}{(+)(-)} = (+)$ [-5/2, 5) $\frac{(+)}{(+)(-)} = (-)$ (5, ∞) $\frac{(+)}{(+)(+)} = (+)$ Thus the solution is $(-7, -5/2] U (5, ∞) $
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