Question Detail
Question
Evaluate ∫ Cos(ln x) / x dx
Correct Answer
Option D is the correct answer.
Detailed Explanation
This integral can be solved using substitution.Let u = ln x.Then, find the differential du:du = d/dx(ln x) dxdu = (1/x) dxNotice that (1/x) dx is present in the integrand. Substitute u and du into the integral:∫ Cos(u) duThis is a standard integral:= sin(u) + CFinally, substitute back u = ln x:= sin(ln x) + CThis matches option D.
Hint
Identify a part of the integrand whose derivative is also present, suggesting a u-substitution.