3X-y+z=3﹛2x+y-3z=11﹛x+y+z=12 3元1次方程.
问题描述:
3X-y+z=3﹛2x+y-3z=11﹛x+y+z=12 3元1次方程.
答
3X-y+z=3 ------(1) 2x+y-3z=11 ------(2),x+y+z=12 ------(3) (1)+(2)得:5x-2z=14 ----(4) (1)+(3) 得:4x+2z=15 -----(5) (4)+(5)得:9x=29 x=29/9 代入(4)得:z=(15-4x)/2=19/18 再代入(3)得 y=12-x-z=12-29/9-19/18=149/18