If it's concave downwards, then we're in a kind of upside down U shape. So f prime prime, our second derivative at x is equal to 0 is equal to what? It's equal to 36 zero squared minus 24 times 0. So that's just 0. So f prime prime, so it's just equal to 0. So we're in neither concave upwards nor concave downwards here. It might be a transition point, it may not.