3)
a) (1,2); (4,5)
f(1) = 2
f(4) = 5
b)
f(4) - f(1) = 5 - 2 = 3
c)
f(4)-f(1)
y = ------------ (x - 1) + f(1)
4 - 1
y = (3/3) (x - 1) + 2
y = 1(x+1) + 2
y = x +3
4)
a)
f(4)-f(1) f(4)-f(1)
------------ > ----------
4 - 1 4 - 3
b)
f(4)-f(1)
------------ < f(1)
4 - 1
