Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 8 - Review - Page 532: 69

Answer

$[-5, 0]$ U $(3/4, ∞)$

Work Step by Step

$x*(x+5)/(4x-3) \ge 0$ $4x-3=0$ $4x-3+3=0+3$ $4x=3$ $4x/4 =3/4$ $x=3/4$ The denominator is zero when $x=3/4$. $x+5=0$ $x+5-5=0-5$ $x=-5$ $x=0$ The numerator is zero when $x=0$ and $x=-5$. Four regions to test: $(-∞, -5]$, $[-5, 0]$, $[0, 3/4)$, $(3/4, ∞)$ Let $x=-6$, $x=-1$, $x=1/2$, $x=1$ $x=-6$ $x*(x+5)/(4x-3) \ge 0$ $-6*(-6+5)/(4*-6-3) \ge 0$ $-6*-1/(-24-3) \ge 0$ $6/-27 \ge 0$ $-2/9 \ge 0$ (false) $x=-1$ $x*(x+5)/(4x-3) \ge 0$ $-1*(-1+5)/(4*-1-3) \ge 0$ $-1*4/(-4-3) \ge 0$ $-4 /-7 \ge 0$ $4/7 \ge 0$ (true) $x=1/2$ $x*(x+5)/(4x-3) \ge 0$ $1/2*(1/2+5)/(4*1/2-3) \ge 0$ $1/2*11/2 / 2-3 \ge 0$ $11/4 / -1 \ge 0$ $-11/4 \ge 0$ (false) $x=1$ $x*(x+5)/(4x-3) \ge 0$ $1*(1+5)/(4*1-3) \ge 0$ $1*6/(4-3) \ge 0$ $6/1 \ge 0$ $6 \ge 0$ (true)
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