Let P1 : y = 4x2 and P2 : y = x2 + 27 be two parabolas. If the area of the bounded region enclosed between P1 and P2 is six times the area of the bounded region enclosed between the line y = x, > 0 and P1, then is equal to :
- 12
- 15
- 8
- 6
Answer
(1) 12
Solution
P1 P2: 4x2 = x2 + 27 x = 3
A1 = -33 (x2 + 27 - 4x2) dx = 2 03 (27 - 3x2) dx
= 2[27x - x3]03 = 2(81 - 27) = 108
Line and P1: x = 4x2 x = 0, 4
A2 = 0 /4 ( x - 4x2) dx = 2 216 - 43 364
= 332 - 348 = 396
Given A1 = 6A2:
108 = 6 396 3 = 1728
= 12
Answer: (1)