$8x -16y=24z -18x=9y -6z; 2x-y+z=54$
Ta có: `8x-16y=24z-18x`
`<=>8x+18x-16y-24x=0`
`<=>26x-16y-24z=0`
`<=>13x-8y-12z=0` $(1)$
`\qquad 8x-16y=9y-6z`
`<=>8x-16y-9y+6z=0`
`<=>8x-25y+6z=0`
`<=>16x-50y+12z=0` $(2)$
Lấy $(1)+(2)$ vế theo vế ta được:
`29x-58y=0<=>29x=58y<=>x=2y`
Thay `x=2y` vào $(1)$
`=>13.2y-8y-12z=0`
`<=>18y-12z=0`
`<=>3y-2z=0<=>2z=3y<=>z=3/ 2 y`
Thay `x=2y;z=3/ 2 y` vào $2x-y+z=54$
`=>2.2y-y+3/ 2 y=54`
`<=>9/ 2 y=54`
`<=>y=54: 9/ 2`
`<=>y=12`
`=>x=2y=2.12=24`
`\qquad z=3/ 2 y=3/ 2 .12=18`
Vậy: `x=24;y=12;z=18`