Ah, I forgot to do the second derivative test and found a maximum instead of a minimum. Then the only critical point you are left with is 0, but 0 isn't positive. So in this situation, you want to find a number closest to this minimum that is in your domain. In this case, it would be:

lim as x->0+ of x, which goes towards 0. Are you sure you didn't mean maximum? That's how this question is usually given.