Functions Question 293

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

[Pb. CET 2000]

Options:

A) e

B) $ e^{2} $

C) $ \frac{1}{2} $

D) 2

Show Answer

Answer:

Correct Answer: D

Solution:

$ \underset{x\to 0}{\mathop{\lim }},\frac{2}{x}\log (1+x)=\underset{x\to 0}{\mathop{\lim }},2\log {{(1+x)}^{\frac{1}{x}}} $ $ =\underset{x\to 0}{\mathop{\lim }},2{\log_{e}}e=2 $ $ { \because \underset{x\to 0}{\mathop{\lim }},{{(1+x)}^{\frac{1}{x}}}={\log_{e}}e=1 } $ Trick : Using L Hospital?s rule.