suatu fungsi dirumuskan dengan g(x)=ax+b.Jika g(-1)=3 dan g(2)=18,maka tentukan nilai a dan b!

g(x ) = ax + b
g(-1) = a(-1) + b = 3
-a + b = 3 .... (1)
g(2) = a(2) + b =18
2a + b = 18 ....(2)

eliminasi b
-a + b = 3
2a + b = 18
___________ _
-3a = -15
a = -15/-3
a = 5

a = 5 disubtitusikan ke persamaan 2
2a + b = 18
2(5) + b = 18
10 + b = 18
b = 18 - 10
b = 8
jadi nilai a = 5 dan nilai b = 8

Kelas 8 Matematika
Bab 2 - Fungsi

g(x) = ax + b
g(-1) = -a + b = 3
g(2) = 2a + b = 18

Eliminasi
-a + b = 3
2a + b = 18
_________ _
-3a = -15
a = -15/-3
a = 5

Substitusikan nilai a
-a + b = 3
-5 + b = 3
b = 3 + 5
b = 8

Nilai
a = 5
b = 8

Fungsi
g(x) = ax + b
g(x) = 5x + 8

g(-1) = 5(-1) + 8
g(-1) = -5 + 8
g(-1) = 3 ✔

g(2) = 5(2) + 8
g(2) = 10 + 8
g(2) = 18 ✔