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MTH 102 MTH 102 Past Questions Objective Question

Question

Obtain dy/dx, if y = acos x
Options
A a<sup>ln a</sup> cos x
B sin x a<sup>cos x</sup> ln a
Correct Answer
C cos x a<sup>cos x - 1</sup>
D sin x a<sup>cos x</sup>
Correct Answer

Option B is the correct answer.

Detailed Explanation

To find the derivative of y = acos x, we use the chain rule for exponential functions of the form d/dx (au) = au ln(a) (du/dx).Here, u = cos x, so du/dx = -sin x.Therefore, dy/dx = acos x ln(a) (-sin x) = -sin x acos x ln(a).Comparing this with the given options, option B is sin x acos x ln a. There appears to be a sign discrepancy in the provided correct option. Based on standard differentiation rules, the correct answer should be negative.

Hint

Recall the derivative rule for an exponential function with a base 'a': d/dx (au) = au ln(a) (du/dx).

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