Question Detail

MTH 102 MTH 102 Past Questions Objective Question

Question

Obtain d/dx [ln(x2 / (x2+1))].
Options
A 2 / (x(x<sup>2</sup>+1))
Correct Answer
B 2 / (x(x<sup>2</sup>+1))
C 5 / (x(x<sup>2</sup>+1))
D 5 / (x(x<sup>2</sup>+1))
Correct Answer

Option A is the correct answer.

Detailed Explanation

First, use logarithm properties to simplify the expression:ln(x2 / (x2+1)) = ln(x2) - ln(x2+1) = 2ln|x| - ln(x2+1).Now, differentiate with respect to x:d/dx (2ln|x| - ln(x2+1)) = 2 * (1/x) - (1/(x2+1)) * (2x)= 2/x - 2x/(x2+1).To combine these terms, find a common denominator:= (2(x2+1) - 2x*x) / (x(x2+1))= (2x2 + 2 - 2x2) / (x(x2+1))= 2 / (x(x2+1)).This matches option A. (Option B is identical to A, so both A and B are technically correct based on the options provided in the image).

Hint

Simplify the logarithmic expression using log properties before differentiating. Recall d/dx(ln(u)) = u'/u.

Question Info