fungsi f di definisikan denagn f (x)=ax+b, jika fungsi f = (-3)= -15 dan f(2)= 0 maka f (-5 ) =

-3a + b = -15
2a + b = 0

Selanjutnya di kurangin, jadi =
 -5a = -15
a = 3 

2(3) + b = 0
6 + b = 0
b = 0

f(-5) = -5(3) + 0 = -15

f(-3)=-3a+b=-15
f(2)=2a+b=0
_____________ -
         -5a=-15
            a=-15/-5
            a= 3
-3a+b=-15
-3x3+b=-15
-9+b=-15
b=-15+9
b=-6

f(-5)=-5a+b
     =-5x3+-6
     =-15-6
     =-21