Question Detail

MTH 102 MTH 102 Past Questions Objective Question

Question

Evaluate ∫ (e2x + e-2x) / (e2x - e-2x) dx
Options
A (1/4)ln|e<sup>2x</sup> - e<sup>-2x</sup>| + C
B (1/2)ln|e<sup>2x</sup> + e<sup>-2x</sup>| + C
C (1/2)ln|e<sup>2x</sup> - e<sup>-2x</sup>| + C
Correct Answer
D (1/4)ln|e<sup>2x</sup> + e<sup>-2x</sup>| + C
Correct Answer

Option C is the correct answer.

Detailed Explanation

This integral can be solved using substitution.Let u = e2x - e-2x.Then, find the differential du:du = d/dx(e2x - e-2x) dxdu = (2e2x - (-2e-2x)) dxdu = (2e2x + 2e-2x) dxdu = 2(e2x + e-2x) dxFrom this, we can see that (e2x + e-2x) dx = (1/2) du.Substitute u and du into the integral:∫ (1/u) * (1/2) du= (1/2) ∫ (1/u) du= (1/2) ln|u| + CFinally, substitute back u = e2x - e-2x:= (1/2) ln|e2x - e-2x| + CThis matches option C.

Hint

Look for a substitution where the numerator is a multiple of the derivative of the denominator.

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