Diketahui sistem persamaan 2x + 2y = 4 dan 4x - 3y = 15 Nilai x + y adalah...

Kelas 8 Matematika
Bab 4 - Sistem Persamaan Linear Dua Variabel

2x + 2y = 4 ......(×2)
4x - 3y = 15 ......(×1)

Eliminasi nilai x
4x + 4y = 8
4x - 3y = 15
_________ _
7y = -7
y = -7/7
y = -1

Substitusikan nilai y
2x + 2y = 4
2x + 2(-1) = 4
2x - 2 = 4
2x = 4 + 2
2x = 6
x = 6/2
x = 3

x + y = 3 + (-1)
x + y = 3 - 1
x + y = 2