Question Detail

MTH 102 MTH 102 Past Questions Objective Question

Question

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

Option C is the correct answer.

Detailed Explanation

This integral is solved using integration by parts, where ∫ u dv = uv - ∫ v du. Let u = ln x (because its derivative simplifies) and dv = 1 dx. Then, du = (1⁄x) dx and v = ∫ 1 dx = x. Substitute these into the integration by parts formula: ∫ ln x dx = (ln x) * x - ∫ x * (1⁄x) dx. ∫ ln x dx = x ln x - ∫ 1 dx. The integral of 1 with respect to x is x. So, ∫ ln x dx = x ln x - x + C. This matches option C.

Hint

Apply integration by parts. Consider which part to choose as 'u' and 'dv' to simplify the integral.

Question Info