Calculus with Applications (10th Edition)

Published by Pearson
ISBN 10: 0321749006
ISBN 13: 978-0-32174-900-0

Chapter 12 - Sequences and Series - 12.7 L'Hospital's Rule - 12.7 Exercises - Page 660: 42

Answer

$+\infty$

Work Step by Step

$$\lim_{x \to \infty}\frac{x^{3}+1}{x^{2}\ln(x)}=\frac{ \infty}{ \infty}$$ Using the l'Hospital's rule it follows: $$\lim_{x \to \infty}\frac{x^{3}+1}{x^{2}\ln(x)}=\lim_{x \to \infty}\frac{3x^{2}}{2x\ln(x)+x^{2}\frac{1}{x}}=\lim_{x \to \infty} \frac{3x^{2}}{2x\ln(x)+x}=\frac{ \infty}{ \infty}$$ Using the l'Hospital's rule second time it follows: $$\lim_{x \to \infty} \frac{3x^{2}}{2x\ln(x)+x}=\lim_{x \to \infty} \frac{6x}{2\ln(x)+2+1}=\frac{ \infty}{ \infty}$$ Using the l'Hospital's rule thirdtime it follows: $$\lim_{x \to \infty} \frac{6x}{2\ln(x)+2+1}=\lim_{x \to \infty} \frac{6}{2\frac{1}{x}}= \lim_{x \to \infty} 3x=+\infty$$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.