3x-y+z=3 2x-y+2z=9 x+3y-2z=-2

题目

3x-y+z=3 2x-y+2z=9 x+3y-2z=-2
ji yong ji yong

答案

3x-y+z=3(1)
2x-y+2z=9(2)
x+3y-2z=-2(3)
(2)+(3)
3x+2y=7(4)
(1)*2+(3)
7x+y=4(5)
(5)*2
14x+2y=8(6)
(6)-(4)
11x=1
x=1/11
y=4-7x=37/11
z=3-3x+y=67/11