Question

Find ∫(3 + 3 cos x)/(x + sin x)dx

Answer 1

Let x + sin x = t

So (1 + cos x)dt = dt

I = 3 ∫dt/t = 3 log |t| + c = 3 log |(x + sin x)| + c

or directly by writing formula

∫(f'(x)/f(x))dx = log |f(x)| + c