You see it's negative, less negative, even less negative, zero, positive, more positive, so it's increasing over the entire place. So if you have a critical point where the derivative is equal to zero, so the slope is equal to zero, and it's concave upwards, you see pretty clearly that we have minimized the function. So what is y going to be equal to? We actually don't even have to figure out what y has to be equal to in order to minimize the sum of squares, we could just put it back into this, but just for fun, we see that y would be negative 16 over x, so y would be equal to negative 4, and we could just figure out now what our sum of squares is. Our minimum sum of squares is going to be equal to, it's going to be equal to four squared, which is 16, plus negative four squared, plus another 16, which is equal to 32. Now I know some of you might be thinking, hey, I could have done this without calculus. I could have just tried out numbers whose product is negative 16, and I probably would have tried out four and negative four in not too much time, and then I would have been able to maybe figure out that it's lower than if I did two and negative eight, or negative two and eight, or one and 16, and that's true.