f(x) = 1-3x, x = 4 , x = 4+h
(a) find the net change of f(x):
f1= f(x=4) = 1-3(4) = 1 - 12 = -11
f2= f(x=4+h) = 1-3(4+h) = 1-12 + 3h = -11 - 3h
Net change = f2 - f1 = -11 -3h - -11 = -3h
(b) average rate of change = slope = (f2 - f1)/(x2-x1) = -3h/((4+h)-4 =-3