And x to the 5 3rds is the same thing as x, as the cube root of x to the 5th. So this is all looking good. Step one looks good. And then step two, it looks like he's trying to find the solution, or he's trying to find x values where the second derivative is equal to zero. And it is indeed true that this has no solution, that you can never make this second derivative equal to zero. In order to be zero, the numerator would have to be zero, and well, two is never going to be equal to zero. So this is correct.