Given below are two statements:
Statement I: x→1limx1−x2=e21
Statement II: x→0lim(x5tan−1x+21loge(1−x1+x)−2x)=52
In the light of the above statements, choose the correct answer from the options given below:
Solutions · 1
Official solution
Statement I: Let x=1+h, h→0: x2/(1−x)=(1+h)−2/h→e−2=e21. True.
Statement II: Using tan−1x=x−3x3+5x5−⋯ and 21loge(1−x1+x)=x+3x3+5x5+⋯:
\[\tan^{-1}x+\frac12\log_e\left(\frac{1+x}{1-x}\right)=2x+\frac{2x^5}{5}+\cdots\]
(the x3 terms cancel). Subtracting 2x and dividing by x5:
\[\lim_{x\to0}\frac{\frac{2x^5}{5}+\cdots}{x^5}=\frac25\]
True. Both statements are true.