Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 1 - Review - Test - Page 137: 8

Answer

A) $x=6$ B)$x=1$ C) $x-4)(x+3)$ D) $-\frac{\sqrt 2}{2}$ and $-\frac{3\sqrt 2}{2}$ E)$[\sqrt 2]=2$ NO SOLUTION F) $(x^{2}-2)(x+1)(x-1)$ G) $x=\frac{22}{3}$. And. $x=\frac{2}{3}$

Work Step by Step

A) $x+5=14-\frac{1}{2}x$ $(x+\frac{1}{2}x)=14-5$ $\frac{3}{2}x=9$ $x=9\div\frac{3}{2}$ $x=6$ B)$\frac{2x}{x+1}=\frac{2x-1}{x}$ Cross multiply $2x^{2}=2x^{2}+x-1$ $2x^{2}-2x^{2}+x-1=0$ $x-1=0$ $x=1$ C) $x^{2}-x-12=0$ $x-4)(x+3)$ D) $2x^{2}+4x+1=0$ Quadratic Formula $\frac{-b\sqrt (b^{2}-4ac)}{2a}$ $\frac{-4\sqrt (4^{2}-4(2)(1))}{2(2)}$ $\frac{-4\sqrt (8)}{4}$ $\frac{-4\sqrt (4\times2)}{4}$ $\frac{-4+2sqrt 2}{4}$. $\frac{-4-2\sqrt 2}{4}$ $\frac{-2\sqrt 2}{4}$. $\frac{-6\sqrt 2}{4}$ $-\frac{\sqrt 2}{2}$ and $-\frac{3\sqrt 2}{2}$ E)$[\sqrt 3-\sqrt (x+5)]=2$ Square both sides $[\sqrt 3^{2}-\sqrt (x+5)]=2^{2}$ $3-\sqrt (x+5)]=4$ $-\sqrt (x+5)]=1$ $\sqrt (x+5)=-1$ Square both sides. $\sqrt (x+5)^{2}]=-1^{2}$ $(x+5)=1$ $x=-4$ Check for extraneous root $[\sqrt 3-\sqrt (-4+5)]=2$ $[\sqrt 3-\sqrt (1)]=2$ $[\sqrt 3-1]=2$ $[\sqrt 2]=2$ NO SOLUTION F) x^{4}-3x^{2}+2=0 $(x^{2}-2)(x+1)(x-1)$ G) $3|x-4|=10$ $|x-4|=\frac{10}{3}$ $(x-4)= \frac{10}{3}$. And. $(x-4)=\frac-{10}{3} $x=\frac{10}{3}+4$. and. $x=\frac-{10}{3}+4$ $x=\frac{22}{3}$. And. $x=\frac{2}{3}$
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