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: 110

Answer

$x=-5$ and $x=2$

Work Step by Step

$x^{1/2}+3x^{-1/2}=10x^{-3/2}$ Rearrage the equation: $x^{1/2}+\dfrac{3}{x^{1/2}}-10x^{-3/2}=0$ Multiply the whole equation by $x^{1/2}$: $x^{1/2}\Big(x^{1/2}+\dfrac{3}{x^{1/2}}-10x^{-3/2}=0\Big)$ $x+3-10x^{-1}=0$ Rewrite $10x^{-1}$ as $\dfrac{10}{x}$ and multiply the whole equation by $x$: $x+3-\dfrac{10}{x}=0$ $x\Big(x+3-\dfrac{10}{x}=0\Big)$ $x^{2}+3x-10=0$ Solve this equation by factoring: $(x+5)(x-2)=0$ Set both factors equal to $0$ and solve each individual equation for $x$: $x+5=0$ $x=-5$ $x-2=0$ $x=2$ The original equation is true for the two solutions found. The final answer is: $x=-5$ and $x=2$
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