Question Detail

MTH 102 MTH 102 Past Questions Objective Question

Question

Evaluate the integral $\int \frac{\cos(\ln x)}{x} dx$.
Options
A $\sec(\ln x) + C$
B $\tan(\ln x) + C$
C $\cot(\ln x) + C$
D $\sin(\ln x) + C$
Correct Answer
Correct Answer

Option D is the correct answer.

Detailed Explanation

This integral can be solved using u-substitution.Let $u = \ln x$.Then, find the differential $du$: $du = \frac{1}{x} dx$.Substitute $u$ and $du$ into the integral:$\int \cos(u) du$The integral of $\cos(u)$ with respect to $u$ is $\sin(u) + C$.Substitute back $u = \ln x$:$\sin(\ln x) + C$.

Hint

Consider a substitution for the argument of the cosine function.

Question Info