The value of the integral -12 e (x + x2 + 1 ) dx is
- 5 - 2 + e ( 7 + 4 51 + 2 )
- 2 - 5 + e ( 7 + 4 51 + 2 )
- 5 - 2 + e ( 9 + 4 51 + 2 )
- 2 - 5 + e ( 9 + 4 51 + 2 )
Answer
(4) 2 - 5 + e ( 9 + 4 51 + 2 )
Solution
Integrating by parts (first function e(x + x2 + 1), whose derivative is 1 x2 + 1):
e (x + x2 + 1 ) dx = x e (x + x2 + 1 ) - x2 + 1
At x = 2: 2 e(2 + 5) - 5; at x = -1: - e( 2 - 1) - 2 = e( 2 + 1) - 2
I = 2 e(2 + 5) - e(1 + 2) - 5 + 2
Since (2 + 5)2 = 9 + 4 5,
I = 2 - 5 + e ( 9 + 4 51 + 2 )
Answer: (4)