
So the answer is choice D. You can check this by differentiating the right hand side and you'll get x^3 back again.
This answer can be found by using the power rule for integrals. That rule is
First you need to multiple minus in second bracket, also in other side you need to multiple - 3 in bracket

Final answer is 0
It's 14 because when you divide you get 13 with a remainder of 58 which is over half of 99 which means that you round up to 14