I have a horrible memory so let me review that I wrote the same thing. 47, 4725, yep, all right. Now, all we know about these are these are both critical points. 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.