1.selesaikan dengan cara substitusi a. x-y =3 dan 2x + 3y =16 b. x+2y = 5 dan 4y -3x =0 c. 3x + y = 7 dan 5x + 3y =7 2.selesaikan dengan cara eliminasi ... a.

1a) x - y = 3
x = y + 3
2x + 3y = 16
2(y + 3) + 3y = 16
2y + 6 + 3y = 16
5y = 16 - 6
y = 10 ÷ 5
y = 2
x = y + 3
x = 2 + 3
x = 5
hp = (5,2)

b) x + 2y = 5
x = - 2y + 5
4y - 3x = 0
4y - 3(-2y + 5) = 0
4y + 6y - 15 = 0
10y = 15
y = 15/10
y = 3/2
x = - 2y + 5
x = - 2(3/2) + 5
x = - 3 + 5
x = 2
hp = (2,3/2)

c) 3x + y = 7
y = - 3x + 7
5x + 3y = 7
5x + 3(-3x + 7) = 7
5x - 9x + 21 = 7
- 4x = - 21 + 7
- 4x = - 14
x = 14/4
x = 7/2
y = - 3x + 7
y = - 3(7/2) + 7
y = - 21/2 + 14/2
y = - 7/2
hp = {7/2 , - 7/2}

2a) 2x - y = 18 |×3
3x + 4y = 5 |×2
6x - 3y = 54
6x + 8y = 10
-------------------(-)
- 11y = - 44
y = 4
2x - y = 18 |×4
3x + 4y = 5
8x - 4y = 72
3x + 4y = 5
------------------(+)
11x = 77
x = 7
hp = (7,4)

b) 2x + 4y = 9
5y - 4x = 8
---------------------(+)
7x = 17
x = 17/7
2x + 4y = 9 |×5
5y - 4x = 8 |×2
10x + 20y = 45
10x - 8x = 16
-----------------------(-)
28y = 29
y = 29/28
hp = {17/7 , 29/28}

c) 4x + 8y = - 4 |×3
3x - 6y = 21 |×4
12x + 24y = - 12
12x - 24y = 84
-----------------------(-)
48y = - 96
y = - 2
4x + 8y = - 4 |×3
3x - 6y = 21 |×4
12x + 24y = - 12
12x - 24y = 84
-----------------------(+)
24x = 72
x = 3
hp = (3,-2)