Determine which of the following statements are NOT NECESSARY in order for a function y = f(x) to be differentiable at x = a. O lim f(a + h) -f(a) = f(a) h - 0 h O lim f(x) = f(a) x - a O lim f(x) = lim f(x) x- a x - at Of(a) ER O lim f ( x ) - fla ) ER x - a x - a