Diketahui fungsi f(x) = ax + b. Jika f(2) = -2 dan f(3) = 13 ,tentukab nilai f(4)

f(x) = ax + b
f(2) = a(2) + b = -2
f(3) = a(3) + b = 13
..
2a + b = - 2
3a + b = 13
---------------- --
- a = - 15
a = 15

2a + b = - 2
2(15) + b = - 2
30 + b = - 2
b = - 2 - 30
b = - 32
maka f(x) = 15x - 32

sehingga f(4) = 15(4) - 32
= 60 - 32
= 28