Diketahui = 2x+y=12 X+3y=21 carilah penyelesaian persamaan diatas ?

Mapel : Matematika
Kelas : VIII SMP
Bab : SPLDV

Pembahasan :
2x + y = 12
x + 3y = 21 —» 2x + 6y = 42

Eliminasi...
2x + 6y = 42
2x + y = 12
——————— (-)
5y = 30
y = 6

Substitusi...
2x + y = 12
2x + 6 = 12
2x = 6
x = 3

Hp : {3 , 6}

x + 3y = 21 | ×2
2x + y = 12 | ×1
----------------
2x + 6y = 42
2x + y = 12
----------------- ¯
5y = 30
y = 6
x = (12 - 6) / 2
= 6/2
= 3