HP sistem persamaan linear tiga variabel 2x+2y+z=12, x+y+2z=3, x+4y+z=20 dengan metode determinan adalah.. (ada di foto soal lbh jelas)

2x+2y+z = 12 …. pers (1)
x + y + 2z = 3 …. pers (2)
x + 4y + z = 20 …. pers (3)

eliminasi 1 dan 2
pers 1 dikali 2

4x+4y+2z = 24
x + y + 2z = 3
_ _ _ _ _ _ _ _ _-
3x + 3y = 21, sederhanakan
x + y = 7 ….. pers (4)

eliminasi 2 dan 3
pers 3 dikali dua

2x+8y+2z = 40
x + y + 2z = 3
_ _ _ _ _ _ _ _ _-
x + 7y = 37 …. pers (5)

pers 4 dan 5 dieliminasi
x+y = 7
x+7y = 37
_ _ _ _ _ _ –
6y = 30
y = 5
masukan ke pers (4)
x+y = 7
x = 7-y = 7-5 = 2

masukan ke pers (2)
x+y+2z = 3
2z = 3-x-y = 3-2-5 = -4
z = -2

jawaban : (2,5,-2) D