So it's 4 minus 12 plus 8, that's going to be 0. So this is equal to 3 over 3, which is equal to 1. f prime of c needs to be equal to 1. And so what is the derivative of this? Well, let's see, f prime of x is equal to 2x minus 6. And so we need to figure out at what x value, especially it has to be within this open interval, at what x value is it equal to 1? So this needs to be equal to 1. So let's add 6 to both sides.