Diketahui x1 dan y1 memenuhi persamaan 2x – 3y = 7 dan 3x – 4y = 9 Nilai x1+ y1= …. A.– 4 B.– 2 C.– 1 D.3 E.4

BAB = Sistem persamaan linear
KELAS = VIII SMP

Pembahasan:
---------------------
2x – 3y = 7 | 3 | 6x – 9y = 21
3x – 4y = 9 | 2 | 6x – 8y = 18-y = - 3
2x – 3y = 7
2x – 3.(-3) = 7
2x + 9 = 7
2x = - 2x = - 1
Jadi x1 + y1 = ( - 1 ) + ( - 3 ) = - 4

Jawaban ( A. )

2x - 3y = 7 | kali 3
3x - 4y = 9 | kali 2
_______________
6x - 9y = 21
6x - 8y = 18 [ - ]
___________
-y = 3
y = -3

2x - 3y = 7
2x - 3(-3) = 7
2x + 9 = 7
2x = 7 - 9
x = -2 / 2
x = -1

x1 + y1 =
-3 + -1 =
-4 [ A ]

#semoga membantu......