Differentiation Question 505

Question: If $ \underset{x\to 0}{\mathop{\lim }},{{(1+asinx)}^{\cos ecx}}=3. $ then a is

Options:

A) ln 2

B) ln 3

C) ln 4

D) $ e^{3} $

Show Answer

Answer:

Correct Answer: B

Solution:

[b] Given $ 3=\underset{x\to 0}{\mathop{\lim }},{{(1+a,sin,x)}^{\cos ec,x}}[{1^{\infty }}form] $ Put $ \sin x=4 $
$ \therefore $ when $ x\to 0,y\to 0 $
$ \therefore \underset{x\to 0}{\mathop{Lim}},{{(1+asinx)}^{\cos ecx}}=\underset{y\to 0}{\mathop{Lim}},{{(1+ay)}^{1/y}}=e^{a} $
$ \therefore e^{a}=3\Rightarrow a={\log_{e}}3=ln,3. $