If the area of the region \(x, y) : ax2 y 1x, 1 x 2, 0 < a < 1 \ is ( e 2) - 17 then the value of 7a - 3 is equal to :
- 1
- 0
- 2
- -1
Answer
(4) -1
Solution
∵ 0 < a < 1 and x 1 ⇒ ax2 < 1x: the region lies between the two curves
[figure]
Area = 12 ( 1x - ax2 )dx = [ e x + ax ]12
= e 2 + a2 - a = e 2 - a2
a2 = 17 a = 27
∴ 7a - 3 = 2 - 3 = -1
Answer: (4)