Limits, Continuity and Differentiability
79554
If \(\lim _{x \rightarrow 0} \frac{\{(a-n) n x-\tan x\} \sin n x}{x^{2}}=0\), where \(n\) is a non-zero real number, then a is equal to
1 0
2 \(\frac{\mathrm{n}+1}{\mathrm{n}}\)
3 \(\mathrm{n}\)
4 \(n+\frac{1}{n}\)
Explanation:
(D) : Given,
\(\lim _{x \rightarrow 0} \frac{\{(a-n) n x-\tan x\} \sin n x}{x^{2}}=0\)
\(\lim _{x \rightarrow 0} \frac{\sin n x}{x} \frac{[(a-n) n x-\tan x]}{x}=0\)
\(\lim _{x \rightarrow 0} n \cdot \frac{\sin n x}{n x}\left[(a-n) n-\frac{\tan x}{x}\right]=0\)
\(\mathrm{n} \times 1[(\mathrm{a}-\mathrm{n}) \mathrm{n}-1]=0\)
\(n[(a-n) n-1]=0\)
\((a-n) n-1=0\)
\((a-n) n=1\)
\(\mathrm{a}-\mathrm{n}=\frac{1}{\mathrm{n}} \Rightarrow \mathrm{a}=\mathrm{n}+\frac{1}{\mathrm{n}}\)