And so we know that something interesting is happening right over here. G prime prime of four is equal to zero. G prime prime of four is equal to zero. So let's think about what the second derivative is when we are less than four. And so, actually, let me just try g prime prime of zero, since that'll be easy to evaluate. G prime prime of zero, well, it's just going to be equal to 48. So when we are less than four, our second derivative, g prime, the second derivative is greater than zero.