Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 1 - Section 1.11 - Solving Equations and Inequalities Graphically - 1.11 Exercises - Page 121: 8

Answer

$x$ = $-4$ and $-2$

Work Step by Step

Given equation is- $\frac{4}{x+2}-\frac{6}{2x}$ = $\frac{5}{2x+4}$ i.e. $\frac{8x-6(x+2)}{2x(x+2)}$ = $\frac{5}{2x+4}$ i.e. $\frac{8x-6x-12}{2x(x+2)}$ = $\frac{5}{2x+4}$ i.e. $\frac{2x-12}{2x(x+2)}$ = $\frac{5}{2x+4}$ i.e. $\frac{2(x-6)}{2x(x+2)}$ = $\frac{5}{2x+4}$ i.e. $\frac{x-6}{x(x+2)}$ = $\frac{5}{2x+4}$ i.e. $(x-6)(2x+4)$ = $5x(x+2)$ i.e. $2x^{2}+4x-12x-24$ = $5x^{2}+10x$ i.e. $5x^{2}+10x -2 x^{2}+8x +24$ = $0$ i.e. $3x^{2}+18x +24$ = $0$ Algebraic Solution: $3x^{2}+18x +24$ = $0$ i.e. $3x^{2}+12x+6x +24$ = $0$ i.e. $3x(x+4)+6(x +4)$ = $0$ i.e. $(x+4)(3x +6)$ = $0$ if $(x+4)$ = $0$, then $x$ = $-4$ if $(3x+6)$ = $0$, then $x$ = $-\frac{6}{3}$ = $-2$ i.e. $x$ = $-4$ and $-2$ are required solutions Graphical Solution: $3x^{2}+18x +24$ = $0$ Now graphing $y$ = $3x^{2}+18x +24$ $x-intercepts$ are $-4$ and $-2$ i.e. $x$ = $-4$ and $-2$ are required solutions
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