Fungsi f ditentukan oleh f(x) = ax + b. Jika f(4) = 5 dan f(−2) = −7, tentukanlah:

F(x) = ax + b
f(4) = 4a + b = 5
f(-2) = -2a + b = -7
—————————- –
              6a = 12
                a = 12/6
                a = 2

4a + b = 5
4(2) + b = 5
8 + b = 5
b = 5-8
b = -3

a. nilai a = 2
    nilai b = -3

b. f(x) = ax + b
    f(x) = 2x – 3