4x + 8y = 24. 10x + 15y = 20. Tentukan nilai x

Mapel : Matematika
Bab : Sistem Persamaan Linear Dua Variabel

Diketahui :
– 4x + 8y = 24
– 10x + 15y = 20

Ditanya :
– Nilai x = …..?

Penyelesaian :
– Nilai x :
4x + 8y = 24
¼(4x + 8y = 24)
x + 2y = 6
2y = 6 – x
y = 3 – x/2

10x + 15y = 20
10x + 15(3 – x/2) = 20
10x + 45 – 15x/2 = 20
2(10x + 45 – 15x/2 = 20)
20x + 90 – 15x = 40
20x – 15x = 40 – 90
5x = – 50
x = – 50/5
x = – 10

Maaf Kalau Salah

4x + 8y = 24 (persamaan 1)
10x + 15y = 20 (persamaan 2)

Eliminasi x untuk mendapatkan nilai y.
4x + 8y = 24 (
10x + 15y = 20 (kali 2)

Hasilnya :
20x + 40y = 120
20x + 30y = 40
10y = 80
Y = 80/10 = 8

Substitusi nilai y ke persamaan 1 untuk mendapatkan nilai x.
4x + 8y = 24
4x = 24 – (8×8)
4x = 24 – 64
4x = -40
X = -40/4 = -10