suatu fungsi dirimuskan f (x)=ax+b. jika f(-2)=10 dan f (-3)=8 maka tentukan nilai f (-7)

f(x) = ax + b
f(-2) = 10 → -2a + b = 10
f(-3) = 8  → -3a + b = 8
                  ____________-
                    a = 2
-2a + b = 10
-2 × 2 + b = 10
-4 + b = 10
b = 10 + 4
b = 14

f(x) = 2x + 14
f(-7) = 2 × (-7) + 14
       = -14 + 14
       = 0

Diket : f (x) = ax + b , f (-2) = 10 , f (-3) = 8

Penyelesaian :
--------------------

f (x) = ax + b
f (-2) = 10
-2a + b = 10 ---> pers.1

f (-3) = 8
-3a + b = 8 ---> pers.2

Eliminasi pers.1 dan 2
-2a + b = 10
-3a + b = 8
_________ _
a = 2

Substitusikan a = 2 ke pers.1 atau 2
-2a + b = 10
-2 (2) + b = 10
-4 + b = 10
b = 10 + 4
b = 14

Maka,
Rumus fungsi f (x)
f (x) = ax + b
f (x) = 2x + 14

Sehingga,
Nilai f (-7)
= 2x + 14
= 2 (-7) + 14
= -14 + 14
= 0

Jawabannya = 0