Remember, we were concave downwards before we got to 2 thirds. So this is consistent. From 0 to 2 thirds, we are concave downwards. And then at 2 thirds, we become concave upwards. Now let's see what happens when x is right less than, when x is just barely less than 0. So once again, f prime, the second derivative of x is equal to 12x times 3x minus 2. Well, right if x was minus point 1 or minus point 001, no matter what, this thing is going to be negative.