Functions Question 217

Question: The value of $ \underset{x\to 0}{\mathop{\lim }},\frac{x\cos x-\log (1+x)}{x^{2}} $ is

[RPET 1999]

Options:

A) ½

B) 0

C) 1

D) None of these

Show Answer

Answer:

Correct Answer: A

Solution:

$ \underset{x\to 0}{\mathop{\lim }},\frac{x\cos x-\log (1+x)}{x^{2}} $ , $ ( \frac{0}{0}form ) $ Applying L-Hospital?s rule, we have $ \underset{x\to 0}{\mathop{\lim }}\frac{\cos x-x\sin x-\frac{1}{x+1}}{2x} $ , $ ( \frac{0}{0}form ) $ $ =\underset{x\to 0}{\mathop{\lim }}\frac{-\sin x-\sin x-x\cos x+\frac{1}{{{(x+1)}^{2}}}}{2}=\frac{1}{2} $ .