Question

How do you evaluate the definite integral `int -x^2/2` from `[-1,2]`?

Answer 1

I found `-3/2`

Explanation:

We first solve the integral and then substitute the extremes of integration:
`int-x^2/2dx=-1/2intx^2dx=-1/2x^3/3=-1/6x^3`
We substitute the extremes and subtract:
`-1/6[2^3-(-1)^3]=-1/6[8+1]=-9/6=-3/2`