Question

Dik: f(x) = px + q
jika f(-1) = 8 dan f(3) = 18 nilai f(-3) adalah..

Answer 1

- p + q = 8
3p + q = 18
__________ _
- 4p = - 10
    p = 5/2
    q = 8 + 5/2 = 21/2
f(x) = (5/2)x + 21/2
f(-3) = (5/2)(-3) + 21/2
      = - 15/2 + 21/2
      = 6/2
      = 3

Answer 2

f(x) = px + q

f(-1) = 8
     8 = -p + q ... [ pers. 1 ]

f(3) = 18
  18 = 3p + q ... [ pers. 2 ]

p = 2,5
q = 10,5

f(-3) = 2,5(-3) + 10,5
        = -7,5 + 10,5
        = 3