Diketahui f(x) = a + bx. Jika f (6) = -13 dan f (-2) = 11, maka rumus fungsi f (x) adalah

Kelas 8 Matematika
Bab Fungsi 

f(x) = a + bx

f(6) = a + 6b = -13
f(-2) = a - 2b = 11

a + 6b = -13
a - 2b = 11
------------------ -
8b = -24
b = -3

a - 2b = 11
a - 2 . (-3) = 11
a = 11 - 6
a = 5

f(x) = 5 - 3x

F(x) = a +bx

F(6) = a +6b = - 13
F(-2) = a - 2b=11
...................... -
8b= - 24
b= - 3
a =11 +2b
= 11 + 2. - 3
=11 - 6 =5

F(x) = a+bx = 5 +(-3)x = 5-3x
Jadi rumua fungsi f(x) = 5-3x