These are points at which our derivative is equal to zero. But we don't know whether they're minimum points. They're points at which the function takes on a minimum value, a maximum value, or neither. To do that, I'll use the second derivative test to figure out if our function is concave upwards or concave downwards or neither at one of these points. So let's look at the second derivative. So P prime prime of x is going to be equal to negative six x plus negative six x plus 12. And so if we look at, let me make sure I have enough space.