diketahui fungsi f (x) =ax +b. jika f (2)=-2 dan f (3) =13, tentukan nilai f(4)

f(x)=ax+b
f(2)=-2
f(3)=13
f(4)=..?
jb:f(x)=ax+b
    f(2)=2a+b=-2..(1)
    f(3)=3a+b=13..(2)
eliminasi b dari 1 dan,sehingga
-a=-15
a=15
2a+b=-2
2.15+b=-2
         b=-32
jadi f(4)=15(4)-32
            =60-32=28
       

f(2) = -2
maka, -2 = 2a + b

f(3) = 13
maka, 13 = 3a + b

-2  = 2a + b
13 = 3a + b
--------------- -
-15 = -a
a = 15
jadi,
b = 13 - 3a
b = 13 - 45
b = -32

maka, f(4) = 15(4) - 32 = 28