Jika 2x + 5y = 11 dan 4x-3y=-17 tentukanlah nilai dari 2x - y

2x + 5y = 11   I x2 I
4x - 3y = -17  I x1 I
-----------------------------
4x + 10y = 22
4x - 3y = -17
------------------------- -
13y = 39
y = 39 / 13
y = 3

2x + 5y = 11
2x + 5(3) = 11
2x + 15 = 11
2x = 11 - 15
2x = -4
x = -4 / 2
x = -2

maka
2x - y
= 2(-2) - 3
= -4 - 3
= -7

2x +5y=11
4x-3y=-17
---------------
4x+10y=22
4x-3y=-17
---------------
13y=39
y=3
4x-3y=-17
4x-3(3)=-17
4x=-17+9
4x=-8
x=-2
jadi 2x-y = 2(-2)-3
=-4-3
=-7