Question

kerjakanlah soal dibawah ini! dengan cara metoda substitusi
1.2y - x = 7 dan x + 2y = 21
2.3x + 2y = 10 dan 3x + 5y = 16
3.3x - 4y = 5 dan 2x + 3y = 8
4.4x + 5y = 7 dan 6x - 10y = 28

PAKE CARA !!!!!!

Answer 1

1. 2y - x = 7
    2y - 7 = x

x + 2y = 21
2y - 7 + 2y = 21
4y = 28
y = 7

x = 2y - 7 = 2(7) - 7 = 14 - 7 = 7

2. 3x + 2y = 10
     y = 5 - 3/2 x
3x + 5y = 16
3x + 5(5 - 3/2 x) = 16
3x + 25 - 15/2 x = 16
6x + 50 - 15 x = 32
-9x = -18
x     = 2

y => 5 - 3/2 x => 5 - 3/2 x 2 => 5 - 3 => 2