ini lagi kak mohon di jawab

f(x) = ax + b

f(2) => 2a + b = 2 ... [i]
f(3) => 3a + b = 5 ... [ii]

Eliminasi ii dengan i

3a + b = 5
2a + b = 2
––––––––– (–)
a = 3

Subs. a = 3 ke 2a + b = 2
2(3) + b = 2
b = -4

f(x) = 3x - 4

Untuk x = 9
f(9) = 3(9) - 4 = 23