Functions Question 165

Question: $ \underset{x\to 0}{\mathop{\lim }},{{{ \tan ( \frac{\pi }{4}+x ) }}^{1/x}}= $

[IIT 1993; RPET 2001]

Options:

A) 1

B) ?1

C) $ e^{2} $

D) $ e $

Show Answer

Answer:

Correct Answer: C

Solution:

Given limit $ =\underset{x\to 0}{\mathop{\lim }},{{( \frac{1+\tan x}{1-\tan x} )}^{1/x}} $ $ =\underset{x\to 0}{\mathop{\lim }},\frac{{{{{{(1+\tan x)}^{1/\tan x}}}}^{(\tan x)/x}}}{{{{{{(1-\tan x)}^{1/\tan x}}}}^{(\tan x)/x}}}=\frac{e}{{e^{-1}}}=e^{2} $ .