The correct option is D ex(3x2−5x+6)+c
∫ex(3x2+x+1)dx
Lets write
3x2+x+1=(ax2+bx+c)+(2ax+b)
Comparing the co-efficients.
a=3;6+b=1;b=−5,c+b=1;c=6
3x2+x+1=(3x2−5x+6)+(6x−5)
∫ex([3x2−5x+6]+(6x−5)]dx
It is in the form of ∫ex(f(x))+f′(x)]=exf(x)+c
So, ∫ex(3x2+x+1)dx=ex(3x2−5x+6)+c