A curve has equation y = f(x). (a) Write an expression for the slope of the secant line through the points P(7, F(7)) and Q(x, f(x)). O f(x)-x (7)-7 x-7 f(x)-7) Of(x)-F(7) x-7 f(7)-7 f(x)-x (b) Write an expression for the slope of the tangent line at P. O lim f(x) f(7) X-O x-7 O lim x-7 x-7 f(x) - F(7) O lim f(x)-f(7) x-7 x-7 Olim f(x)-> x-0 (7)-7