We need to come up with the original function knowing the derivative. So if F prime of X equals two X + 5, what gives us out a derivative of 2X? And if we use the power, we're going to add 1 to the exponent and divide by the new exponent now, so we're going to get X ^2 plus, what gives us out the derivative of five? Well, when five is the coefficient on a linear term, so 5X plus there's some constant because the derivative of every constant is 0. So once we get F of X equal X ^2 + 5 X plus C, then we're going to stick a -1 for our X and four for our Y. And we're going to solve for the CC is going to equal 8, so F of X = X ^2 + 5 X +8.