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: 30

Answer

$\lim_{t\to0}\Big(\dfrac{1}{t}-\dfrac{1}{t^{2}+t}\Big)=1$

Work Step by Step

$\lim_{t\to0}\Big(\dfrac{1}{t}-\dfrac{1}{t^{2}+t}\Big)$ Try to evaluate the limit applying direct substitution: $\lim_{t\to0}\Big(\dfrac{1}{t}-\dfrac{1}{t^{2}+t}\Big)=\dfrac{1}{0}-\dfrac{1}{0^{2}+0}=\infty-\infty$ Indeterminate form The limit could not be evaluated using direct substitution. Evaluate the subtraction of fractions and simplify: $\lim_{t\to0}\Big(\dfrac{1}{t}-\dfrac{1}{t^{2}+t}\Big)=\lim_{t\to0}\Big[\dfrac{(t^{2}+t)-t}{t(t^{2}+t)}\Big]=...$ $...=\lim_{t\to0}\dfrac{t^{2}}{t(t^{2}+t)}=\lim_{t\to0}\dfrac{t^{2}}{t^{2}(t+1)}=\lim_{t\to0}\dfrac{1}{t+1}=...$ Try to evaluate the limit using direct substitution again: $\lim_{t\to0}\dfrac{1}{t+1}=\dfrac{1}{0+1}=1$
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