NTA Abhyas JEE Main2020MathematicsArea Under CurvesPractice
The area of the region enclosed by f x = - 2 x e x and the x -axis is
Options
- A1 sq. unit
- B2 sq. units
- C1 2 sq. unit
- Dnot defined
Correct answer
B. 2 sq. units
Step-by-step solution
f x = - 2 x e - x f ' x = 2 x e - x - 2 e - x = 2 e - x x - 1 Area = ∫ 0 ∞ - 2 x e - x d x = 2 ∫ 0 ∞ x e - x d x = - x e - x 0 ∞ + ∫ 0 ∞ e - x d x = 2 0 - e - x 0 ∞ = 2 × 1 = 2