Limits Continuity And Differentiability Question 34

Question: If $ y=\sqrt{\log x+\sqrt{\log x+\sqrt{\log x+…..\infty }}} $ , then $ \frac{dy}{dx}= $

Options:

A) $ \frac{x}{2y-1} $

B) $ \frac{x}{2y+1} $

C) $ \frac{1}{x(2y-1)} $

D) $ \frac{1}{x(1-2y)} $

Show Answer

Answer:

Correct Answer: C

Solution:

$ y=\sqrt{\log x+y}\Rightarrow y^{2}=\log x+y $

$ \Rightarrow 2y\frac{dy}{dx}=\frac{1}{x}+\frac{dy}{dx}\Rightarrow \frac{dy}{dx}=\frac{1}{x(2y-1)} $