rumus fungsi f(x)=ax+b . jika f(3)=15 dan f(2)=21 tentukan 1. nilai a dan b , 2. bentuk fungsi , 3. nilai f(-11)​

f(x) = ax + b

f(3) = 15

[1] 3a + b = 15

f(2) = 21

[2] 2a + b = 21

Eliminasi [1] – [2]

a = -6

Subtitusikan a = -6 ke [2]

2(-6) + b = 21

-12 + b = 21

b = 33

Bentuk fungsi:

f(x) = -6x + 33

f(11)

= -6(11) + 33

= -66 + 33

= -33