ExamBro
ExamBro
TS EAMCET · Maths · Differentiation

If \(y=x+\tan x\), then \(\cos ^2 x \frac{d^2 y}{d x^2}+2 x\) is equal to

  1. A -2 y
  2. B \(\frac{2}{3} y\)
  3. C 3y
  4. D 2y
Verified Solution

Answer & Solution

Correct Answer

(D) 2y

Step-by-step Solution

Detailed explanation

Given, \(y=x+\tan x\) Differentiating, \(\frac{d y}{d x}=1+\sec ^2 x\) Again differentiating, \(\frac{d^2 y}{d x^2}=0+2 \sec x \sec x \tan x\) \[ =2 \sec ^2 x \cdot \tan x \] Now, \(\cos ^2 x \cdot \frac{d^2 y}{d x^2}+2 x=\cos ^2 x \cdot 2 \sec ^2 x \cdot \tan x+2 x\)…