Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 1 - Section 1.5 - Equations - 1.5 Exercises - Page 57: 117

Answer

The solution to this equation is $x=-\dfrac{1}{2}$

Work Step by Step

$\dfrac{1}{x^{3}}+\dfrac{4}{x^{2}}+\dfrac{4}{x}=0$ Multiply the whole equation by $x^{3}$: $x^{3}\Big(\dfrac{1}{x^{3}}+\dfrac{4}{x^{2}}+\dfrac{4}{x}=0\Big)$ $1+4x+4x^{2}=0$ Rearrange: $4x^{2}+4x+1=0$ This is a perfect square trinomial, factor it: $(2x+1)^{2}=0$ Take the square root of both sides: $\sqrt{(2x+1)^{2}}=\sqrt{0}$ $2x+1=0$ Solve for $x$: $2x=-1$ $x=-\dfrac{1}{2}$ The solution to this equation is $x=-\dfrac{1}{2}$
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