Q. If $\lim_{x\to\infty}\left(\left(\frac e{1-e}\right)\left(\frac1e-\frac x{1+x}\right)\right)^x=\alpha$, then the value of $\frac{\log_e\alpha}{1+\log_e\alpha}$ equals :

A) $e^{-1}$
B) $e^2$
C) $e^{-2}$
D) $e$
Explanation

[Solution by Dr. Abubacker] The base simplifies to $\frac{1+(1-e)x}{(1-e)(1+x)}=1+\frac{e}{(1-e)(1+x)}$, so it is of the form $1^\infty$ and $\alpha=e^{\,e/(1-e)}$. Then $\ln\alpha=\frac e{1-e}$ and $\frac{\ln\alpha}{1+\ln\alpha}=\frac{e/(1-e)}{1/(1-e)}=e$. Answer (4).

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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