$\int \frac{x \cos x}{(x \sin x+\cos x)^2} d x$ is equal to
Answer & explanation
Correct answer: option 2
Let $I=\int \frac{x \cos x}{(x \sin x+\cos x)^2} d x$
Let $\frac{1}{x \sin x+\cos x}= t \Rightarrow \frac{(x \sin x+\cos x) . 0-1(x \cos x+\sin x-\sin x)}{(x \sin x+\cos x)^2}=\frac{d t}{d x}$
$\Rightarrow \frac{-x \cos x}{(x \sin x+\cos x)^2}=\frac{d t}{d x}$
∴ $I=-\int d t=-\frac{1}{x \sin x+\cos x}+c$
Hence (2) is the correct answer.