JEE Main202312 Apr 2023Morning ShiftMathematicsApplication of DerivativesActual
If the total maximum value of the function f x = 3 e 2 sin x sin 2 x , x ∈ 0 , π 2 , is k e , then k e 8 + k 8 e 5 + k 8 is equal to
Options
- Ae 3 + e 6 + e 11
- Be 5 + e 6 + e 11
- Ce 3 + e 6 + e 10
- De 3 + e 5 + e 11
Correct answer
A. e 3 + e 6 + e 11
Step-by-step solution
Given function is f x = 3 e 2 sin x sin 2 x For maxima or minima f ' ( x ) = 0 f ' x = f x 2 sin x cos x × ln 3 e 2 sin x + sin 2 x 1 × 2 sin x 3 e × 3 e 2 - 1 sin 2 x × cos x ⇒ f x sin 2 x ln 3 e 2 sin x - sin x cos x = 0 Now on equation we get, sin 2 x = 0 (not possible) So, ln 3 e 2 sin x = + 1 2 ⇒ 3 × e 2 sin x = e 1 2 ⇒ sin x = 3 2 ⇒ f max = e 3 8 = e 11 8 e ⇒ k = e 11 8 ⇒ k e 8 + k 8 e 5 + k 8 = e 3 + e 6 + e 11