Differentiation Question 214

Question: If $ y=\frac{\tan x+\cot x}{\tan x-\cot x}, $ then $ \frac{dy}{dx}= $

Options:

A) $ 2\tan 2x\sec 2x $

B) $ \tan 2x\sec 2x $

C) $ -\tan 2x\sec 2x $

D) $ -2\tan 2x\sec 2x $

Show Answer

Answer:

Correct Answer: D

Solution:

$ y=\frac{\tan x+\cot x}{\tan x-\cot x}=-\frac{1+{{\tan }^{2}}x}{1-{{\tan }^{2}}x}=-\sec 2x $

$ \Rightarrow \frac{dy}{dx}=-2\sec 2x\tan 2x $ .