4 x + 12y=28
2x+y=21
Persamaan Linear Dua Variabel (PLDV)
Dik:
4x + 12y = 28
2x + y = 21
Dit:
Nilai x dan y?
Jawab:
4x + 12y = 28 |1| 4x + 12y = 28
2x + y = 21 |2| 4x + 4y = 84
___________-
8y = - 56
y = -56/8
y = -7
4x + 12y = 28
4x + 12(-7) = 28
4x + (-84) = 28
4x = 28 + 84
4x = 112
x = 28
HP = {-7,28}
atau Nilai x = 28 dan Nilai y = -7
Penjelasan dengan langkah-langkah:
4x + 12y = 28 pers(1)
2x + y = 21 pers(2)
Eliminasi pers(1) dan (2)
4x + 12y = 28 |×1| 4x + 12y = 28
2x + y = 21 |×2| 4x + 2y = 42
——————— -
10y = -14
y = -14/10
y = -7/5
Substitusi y = -7/5 ke pers(2)
2x + y = 21
2x + (-7/5) = 21
2x - 7/5 = 21
2x = 21 + 7/5
2x = 105/5 + 7/5
2x = 112/5
x = (112/5)/2
x = 112/(5×2)
x = 112/10
x = 56/5
HP{56/5, -7/5}
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