Tolong dibantu No 1 sama No 3 Besok mau dikumpulin

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Semoga benar semua

1)
a.
y = -1/2x+4
kedua ruas dikalikan 2
2y = -x + 8
x + 2y - 8 = 0

koef x = 1
koef y = 2
konstanta = -8

b.
3x-4y-2 = 0
koef x = 3
koef y = -4
konstanta = -2

c.
-x+2y = -1
-x+2y + 1 = 0
dikali -1
x - 2y - 1 = 0
koef x = 1
koef y = -2
konstanta = -1

3)
a.
2x-3y = 7
2x+y = 3
________ -

-4y = 4
y = -1

2x-3y = 7
2x-3(-1) = 7
2x+3 = 7
2x = 4
x = 2

b.
x-y = 1 |×3|
3x-y = 9 |×1|

3x-3y = 3
3x-y = 9
_______ -
-2y = -6
y = 3

x-y = 1
x-(3) = 1
x = 4