Precalculus: Mathematics for Calculus, 7th Edition

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

Chapter 13 - Section 13.2 - Finding Limits Algebraically - 13.2 Exercises - Page 913: 16

Answer

$\lim_{x\to0}\Big(\dfrac{-5x^{20}-2x^{2}+3000}{x^{2}-1}\Big)^{1/3}=-10\sqrt[3]{3}$

Work Step by Step

$\lim_{x\to0}\Big(\dfrac{-5x^{20}-2x^{2}+3000}{x^{2}-1}\Big)^{1/3}$ Apply the Limit of a Power law: $\lim_{x\to0}\Big(\dfrac{-5x^{20}-2x^{2}+3000}{x^{2}-1}\Big)^{1/3}=...$ $...=\Big[\lim_{x\to0}\Big(\dfrac{-5x^{20}-2x^{2}+3000}{x^{2}-1}\Big)\Big]^{1/3}=...$ Apply the Limit of a Quotient law: $...=\Big[\dfrac{\lim_{x\to0}(-5x^{20}-2x^{2}+3000)}{\lim_{x\to0}(x^{2}-1)}\Big]^{1/3}=...$ Apply the Limit of a Sum and a Difference in the numerator and in the denominator: $...=\Big[\dfrac{\lim_{x\to0}-5x^{20}-\lim_{x\to0}2x^{2}+\lim_{x\to0}3000}{\lim_{x\to0}x^{2}-\lim_{x\to0}1}\Big]^{1/3}=...$ Apply the Limit of a Constant Multiple law to the first two terms in the numerator and the Limit of a Power law to the first term of the denominator: $...=\Big[\dfrac{-5\lim_{x\to0}x^{20}-2\lim_{x\to0}x^{2}+\lim_{x\to0}3000}{(\lim_{x\to0}x)^{2}-\lim_{x\to0}1}\Big]^{1/3}=...$ Apply the Limit of a Power law to the first two terms of the numerator: $...=\Big[\dfrac{-5(\lim_{x\to0}x)^{20}-2(\lim_{x\to0}x)^{2}+\lim_{x\to0}3000}{(\lim_{x\to0}x)^{2}-\lim_{x\to0}1}\Big]^{1/3}=...$ Evaluate: $...=\Big[\dfrac{-5(0)^{20}-2(0)^{2}+3000}{(0)^{2}-1}\Big]^{1/3}=\Big(\dfrac{3000}{-1}\Big)^{1/3}=...$ $...=\sqrt[3]{-3000}=-10\sqrt[3]{3}$
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