Tentukan himpunan penyelesaian dari sistem persamaan berikut. A. X-y = 1 dan x+y=7 B. X+y= 6 dan x-y= 0 C. X+y =3 dan x+3y=4 D. 4x-5y=-12 dan 2x+3y= 16 E.

a) x - y = 1
x + y = 7
---------------(-)
2y = - 6
y = - 3
subtitusi
x - y = 1
x + 3 = 1
x = 1 - 3
x = - 2
hp = ( -2 , - 3 )

b) x + y = 6
x - y = 0
-----------------(-)
2y = 6
y = 3
subtitusi
x - y = 0
x - 3 = 0
x = 3
hp = ( 3,3 )

c) x + y = 3
x + 3y = 4
----------------(-)
- 2y = - 1
y = ½
subtitusi
x + y = 3
x + ½ = 3
x = 3 - ½
x = 2½
x = 5/2
hp = ( 5/2 , ½ )

d) 4x - 5y = 12
2x + 3y = 16 |×2
maka
4x - 5y = 12
4x + 6y = 32
------------------(-)
- 11y = - 20
y = 20/11
• 4x - 5y = 12 |×3
2x + 3y = 16 |×5
maka
12x - 15y = 36
10x + 15y = 80
---------------------(+)
22x = 116
x = 116/22
x = 58/11
hp = ( 58/11 , 20/11 )

e) 2x + 3y = 8 |×3
3x + 2y = 7 |×2
maka
6x + 9y = 24
6x + 4y = 14
-------------------(-)
5y = 10
y = 2
subtitusi
2x + 3y = 8
2x + 3(2) = 8
2x + 6 = 8
2x = 8 - 6
2x = 2
x = 1
hp = ( 1,2 )

f) x + 2y = 10
½x - y = - 1 |×2
maka
x + 2y = 10
x - 2y = - 2
----------------(-)
4y = 12
y = 3
subtitusi
x + 2y = 10
x + 2(3) = 10
x + 6 = 10
x = 10 - 6
x = 4
hp = ( 4,3 )