X + 3y + 5z = 21 4x + 2y + z = 92x + y + 2z = 12

X + 3y + 5z = 21 4x + 2y + z = 92x + y + 2z = 12

Eliminasi z:
$20x +10y + 5z = 45 : dikurangi \ x + 3y + 5z = 21 \ 19x + 7y = 24 : : .....(1) \ \ 8x + 4y + 2z = 18 : dikurangi \ 2x + y + 2z = 12 \ 6x + 3y = 6 : : .....(2)\$
Eliminasi persamaan (1) dan (2):
$57x + 21y = 72: dikurangi \ 42x + 21y = 42 \ 15x = 30 \ x = 2 \ \ 12 + 3y = 6 \ 3y = -6 \ y = - 2 \ \ 4x + 2y + z = 9 \ 8 - 4 + z = 9 \ z = 5$