JEE Main202225 Jul 2022Morning ShiftMathematicsApplication of DerivativesActual
If the absolute maximum value of the function f x = x 2 - 2 x + 7 e 4 x 3 - 12 x 2 - 180 x + 31 in the interval - 3 , 0 is f α , then
Options
- Aα = 0
- Bα = - 3
- Cα ∈ - 1 , 0
- Dα ∈ - 3 , - 1
Correct answer
B. α = - 3
Step-by-step solution
Given, f x = x 2 - 2 x + 7 e 4 x 3 - 12 x 2 - 180 x + 31 Now differentiating the function to find function is increasing or decreasing, f ' x = e 4 x 3 - 12 x 2 - 180 x + 31 12 x 2 - 2 x - 15 + 2 x - 1 ⇒ f ' x = e 4 x 3 - 12 x 2 - 180 x + 31 12 x + 3 x - 5 + 2 x - 1 ⇒ f ' x < 0 for x ∈ - 3 , 0 So, f x is decreasing function on - 3 , 0 The absolute maximum value of the function f x is at x = - 3 ⇒ α = - 3