The integral 01 -1 (1+x+x2 )dx is equal to :
- 2 -12+ 12 e ( 54 )+ 2
- 2 -12+ 12 e ( 54 )- 2
- 2 -12- 12 e ( 54 )+ 2
- 2 -12- 12 e ( 54 )- 2
Answer
(4) 2 -12- 12 e ( 54 )- 2
Solution
For x 0: -1 (1+x+x2 )= -1 11+x(x+1)= -1 (x+1)-x1+x(x+1)
= -1(x+1)- -1x
I= 01 -1(x+1) dx- 01 -1x dx= 12 -1u du- 01 -1x dx
By parts: -1u du=u -1u- 12 e (1+u2 )
12 -1u du=2 -12- 12 e5- 4+ 12 e2
01 -1x dx= 4- 12 e2
I=2 -12- 12 e5+ e2- 2
=2 -12- 12 e ( 54 )- 2 ( e2= 12 e4)
Answer: (4)