Intermediate Algebra (6th Edition)

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

Chapter 8 - Review - Page 531: 36

Answer

$(-∞, -6)$ U $(-3/4,0)$ U $(5,∞)$

Work Step by Step

$(4x+3)(x-5)/x*(x+6) > 0$ $x+6=0$ $x+6-6=0-6$ $x=-6$ The denominator is zero when $x=0$ and $x=-6$. $4x+3=0$ $4x+3-3=0-3$ $4x=-3$ $4x/4=-3/4$ $x=-3/4$ $x-5=0$ $x-5+5=0+5$ $x=5$ The numerator is zero when $x=-3/4$ and $x=5$. Five regions to test: $(-∞, -6)$, $(-6, -3/4)$, $(-3/4,0)$, $(0,5)$, $(5,∞)$ Let $x=-10$, $x=-1$, $x=-1/2$, $x=1$, $x=6$ $x=-10$ $(4x+3)(x-5)/x*(x+6) > 0$ $(4*-10x+3)(-10-5)/-10*(-10+6) > 0$ $(-40+3)*-15/-10*(-4) > 0$ $-37*-15/40 >0$ $555/40 > 0$ $13.875 > 0$ (true, so this region is part of the solution set) $x=-1$ $(4x+3)(x-5)/x*(x+6) > 0$ $(4*-1+3)(-1-5)/-1*(-1+6) > 0$ $(-4+3)*-6/-1*5 >0$ $-1*-6 /-5 >0$ $6/-5 >0$ $-6/5 > 0$ (false, so this region is not part of the solution set) $x=-1/2$ $(4x+3)(x-5)/x*(x+6) > 0$ $(4*-1/2+3)(-1/2-5)/-1/2*(-1/2+6) > 0$ $(-2+3)(-11/2)/-1/2*(5.5) >0$ $1*-5.5 /-1/2 *(5.5) >0$ $-1/ -1/2 > 0$ $1/ .5 >0$ $2 > 0$ (true, so this region is part of the solution set) $x=1$ $(4x+3)(x-5)/x*(x+6) > 0$ $(4*1+3)(1-5)/1*(1+6) > 0$ $(4+3)*-4/1*7 >0$ $7*-4/7 >0$ $-4 >0$ (false, so this region is not part of the solution set) $x=6$ $(4x+3)(x-5)/x*(x+6) > 0$ $(4*6+3)(6-5)/6*(6+6) > 0$ $(24+3)*1/6*12 > 0$ $27*1/72 >0$ $27/72 > 0$ $9/24 >0$ $3/8 >0$ (true, so this region is part of the solution set)
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