Jawabanmu

2014-08-29T14:57:52+07:00
F(x) = 4 × 12 -8
      = 48 -8
      = 40

Semoga benar !!
1 3 1
2014-08-29T15:01:50+07:00
F (x) = 4x - 8
f (k) = 4k - 8

Maka :
f (k) = 12
4k - 8 = 12
4k = 12 + 8
4k = 20
k = 20/4
k = 5