Differentiation Question 22

Question: If $ x={e^{y+{e^{y+….to\infty }}}} $ , $ x>0, $ then $ \frac{dy}{dx} $ is

[AIEEE 2004]

Options:

A) $ \frac{1+x}{x} $

B) $ \frac{1}{x} $

C) $ \frac{1-x}{x} $

D) $ \frac{x}{1+x} $

Show Answer

Answer:

Correct Answer: C

Solution:

$ x={e^{y+{e^{y+….to\infty }}}} $ , $ x>0 $ , $ x={e^{y+x}} $

Taking log to the both sides, $ \log x=(y+x) $

Differentiate both sides w.r.t. x, $ \frac{1}{x}=\frac{dy}{dx}+1 $

$ \Rightarrow \frac{dy}{dx}=\frac{1-x}{x} $ .