Question Detail

MTH 102 MTH 102 Past Questions Objective Question

Question

Find dy/dx if y = esin2x / cos2x.
Options
A 2e<sup>sin2x</sup> [1 - sec2x tan2x]
B 2e<sup>sin2x</sup> [1 - sec2x cos2x]
C 2e<sup>sin2x</sup> [1 + sec2x tan2x]
Correct Answer
D 2e<sup>sin2x</sup> [1 + sec2x cos2x]
Correct Answer

Option C is the correct answer.

Detailed Explanation

We can rewrite the function as a product: y = esin2x (cos2x)-1.Now apply the product rule: d/dx(uv) = u'v + uv'.Let u = esin2x. Then u' = d/dx(esin2x) = esin2x * (d/dx(sin2x)) = esin2x * (cos2x * 2) = 2cos2x esin2x.Let v = (cos2x)-1. Then v' = d/dx((cos2x)-1) = -1(cos2x)-2 * (d/dx(cos2x))= -(cos2x)-2 * (-sin2x * 2) = 2sin2x / (cos2x)2.Substitute into the product rule:dy/dx = (2cos2x esin2x)(cos2x)-1 + (esin2x)(2sin2x / (cos2x)2)dy/dx = 2esin2x + esin2x (2sin2x / (cos2x)2)Factor out 2esin2x:dy/dx = 2esin2x [1 + sin2x / (cos2x)2]Rewrite the term inside the bracket:sin2x / (cos2x)2 = (sin2x / cos2x) * (1 / cos2x) = tan2x * sec2x.So, dy/dx = 2esin2x [1 + tan2x sec2x].This matches option C.

Hint

Rewrite the function as a product y = u*v where u = esin2x and v = (cos2x)-1. Then apply the product rule and chain rule. Simplify using trigonometric identities tan x = sin x / cos x and sec x = 1 / cos x.

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