F(x)= x² + 5, is just a parabola shfited upwards by 5 units, so, is a smooth graph and no abrupt edges, so from 0 to 3, is indeed differentiable and continuous. So Rolle's theorem applies, let's check for "c" by simply setting its variable to 0, bear in mind that, looking for "c" in this context, is really just looking for a critical point, since we're just looking where f'(c) = 0, and is a horizontal tangent line.
