Consider the following equation: W) = Hm u + h) , u) hail h Let an) : 3'5 If 0, 51$ 0, use the above formula to nd f' (a) : Hint: use the formula (0. * b)(a.2 + ab + 5") : a3 i b3 Now show that f' (0) does not exist and that f has a vertical tangent line at (0,0)