Question Detail

MTH 102 MTH 102 Past Questions Objective Question

Question

Simplify ∫ ln x dx
Options
A <i>xlnx+x<sup>2</sup>+C</i>
B <i>x-x<sup>2</sup> lnx+C</i>
C <i>xlnx-x+C</i>
Correct Answer
D <i>x<sup>2</sup>-lnx<sup>2</sup>+C</i>
Correct Answer

Option C is the correct answer.

Detailed Explanation

This integral requires integration by parts: ∫ u dv = uv - ∫ v du.To integrate ln x, we choose u = ln x and dv = dx.Then, differentiate u to find du: du = (1/x) dx.And integrate dv to find v: v = ∫ dx = x.Substitute these into the integration by parts formula:∫ ln x dx = (ln x) ∙ x - ∫ x ∙ (1/x) dx= x ln x - ∫ 1 dx.Now, integrate ∫ 1 dx = x.So, ∫ ln x dx = x ln x - x + C. This matches option C.

Hint

When integrating ln x, use integration by parts. A common strategy is to set u = ln x and dv = dx.

Question Info