tolong bangetttt pake cara kerjanya pliisss dibantu besok mau dikumpulin

f(x)=ax+b
f(-1)=a(-1)+b=2
f(2)=a(2)+b=11
--------------------. -
-3a=-9
a=3


f(x)=ax+b
f(2)=a(2)+b=-2
f(3)=a(3)+b=13
--------------------. -
-a=-15
a=15

ax+b=-2
(15).(2)+b=-2
b=-32

f(4)=15.4+(-32)
f(4)=28