diketahui suatu fungsi f (x)=ax+b memiliki nilai f(-1)=1 dan f(2)=13.nilai f(4) adalah

Kelas 8 Matematika
Bab Fungsi

f(x) = ax + b

f(-1) = -a + b = 1
f(2) = 2a + b = 13

2a + b = 13
-a + b = 1
------------------ -
3a = 12
a = 4

-a + b = 1
-4 + b = 1
b = 1 + 4
b = 5

f(x) = 4x + 5

f(4) = 4 . 4 + 5
f(4) = 16 + 5
f(4) = 21