Diketahui f(x)=ax+b.jika f(-4)=6 dan f(6)=-4,maka tentukan nilai f(2)

Kelas 8 Matematika
Bab Persamaan Linear

f(x) = ax + b

f(-4) = -4a + b = 6
f(6) = 6a + b = -4
………. ——————- –
– 10a = 10
a = -1

6a + b = -4
6 . (-1) + b = -4
b = -4 + 6
b = 2

f(x) = -x + 2

f(2) = -2 + 2
f(2) = 0

F(x) = ax + b
f(-4) = a.-4 + b
6 = -4a + b •••• (1)
f(6) = a.6 + b
-4 = 6a + b ••• (2)

-4a + b = 6
6a + b = -4
—————- –
-10a = 10
a = -1

-4a + b = 6
-4.-1 + b = 6
4 + b = 6
b = 2

Maka,
f(x) = ax + b
f(2) = -1.2 + 2
•••• = -2 + 2
•••• = 0