Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

If $f(x)=\frac{1}{4-3\cos^2x+5\sin^2x}$ and its anti-derivative $F(x)=\frac{1}{3}\tan^{-1}(g(x))+C$ then g(x) =

Options:

$3 \tan x$

$\sqrt{2}\tan x$

$2 \tan x$

None of these

Correct Answer:

$3 \tan x$

Explanation:

$F(x)=\frac{1}{4-3\cos^2x+5\sin^2x}=\int\frac{\sec^2x\,dx}{4(1+\tan^2x)-3+5\tan^2x}$

Put tan x = t to get $F(x)=\int\frac{dt}{9t^2+1}+C=\frac{1}{3}\tan^{-1}(3t)+C=\frac{1}{3}\tan^{-1}(3\tan x)+C$