NTA Abhyas JEE Main2020MathematicsArea Under CurvesPractice
The value of the parameter ‘a' such that the area bounded by y = a 2 x 2 + a x + 1 , coordinate axes and the line x = 1 attains its least value, is equal to
Options
- A- 1 4
- B- 1 2
- C- 3 4
- D- 1
Correct answer
C. - 3 4
Step-by-step solution
a 2 x 2 + a x + 1 is  positive for all real values of x . ∴ Area = ∫ 0 1 a 2 x 2 + a x + 1 d x = a 2 3 + a 2 + 1 = 1 6 2 a 2 + 3 a + 6 = 1 6 2 a 2 + 3 2 a + 9 16 + 6 - 18 16 = 1 6 2 a + 3 4 2 + 39 8 , which is minimum for a = - 3 4