4 01 ( 1 3 + x2 + 1 + x2 )dx - 3 e( 3) is equal to :
- 2 - 2 - e(1 + 2)
- 2 + 2 + e(1 + 2)
- 2 + 2 - e(1 + 2)
- 2 - 2 + e(1 + 2)
Answer
(1) 2 - 2 - e(1 + 2)
Solution
Rationalise: 1 3 + x2 + 1 + x2 = 3 + x2 - 1 + x2(3 + x2) - (1 + x2) = 3 + x2 - 1 + x22
4 01 ( ) dx = 2 01 3 + x2 dx - 2 01 1 + x2 dx
Using x2 + a2 dx = x2 x2 + a2 + a22 e |x + x2 + a2 | + C:
01 3 + x2 dx = 12(2) + 32 e 3 - 32 e 3 = 1 + 34 e 3
01 1 + x2 dx = 22 + 12 e(1 + 2)
4 01 ( ) dx = 2 + 32 e 3 - 2 - e(1 + 2)
3 e 3 = 32 e 3
Required value = 2 - 2 - e(1 + 2)
Answer: (1)