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Question

Mathematics Question on Limits

For x > 0, limx0[(sinx)1/x+(1x)sinx]lim_{ x \to 0} \Bigg [ (sin \, x)^{1/x} + \bigg( \frac{1}{x}\bigg)^{sin \, x} \Bigg ] is

A

0

B

-2

C

1

D

2

Answer

1

Explanation

Solution

Here, limx to0(sin x)1/x+limx0(1x)sin xlim_{ x \ to 0} (sin \ x)^{1/x} + lim_{x \to 0} \bigg(\frac{1}{x}\bigg)^{sin \ x}
= 0 + limx0elog(1x)sin x= elimx0log (1/x)cosec x lim_{ x \to 0} e^{log \bigg(\frac{1}{x}\bigg)^{sin \ x} } = \ e^{lim_{ x \to 0} \frac{log \ (1 / x)}{cosec \ x}} \hspace21mm \Bigg [ \begin{array} \ lim_{ x \to 0} (sin \ x)^{1/x} \rightarrow 0 \\\ as, (decimal)^\infty \ \ \rightarrow 0 \end{array} \Bigg ]
Appling L'Hospital's rule, we get
elimx0x(1x2)cosec x cot x=elimx0sin xxtan x=e0=1e^lim_{x \to 0 } \frac{ x \bigg( - \frac{1}{x^2}\bigg)}{ - cosec \ x \ cot \ x} = e^{lim_{x \to 0 } \frac{sin \ x}{ x} tan \ x} = e^0 = 1