3道解三元一次方程组!(1)7x+2y-z=7 (2)9x+4y+z=10 (3)5x-3y+6z=-36x-y+z=7 -9x+2y+3z=-6 2x-y+3=04x+3y+z=9 3x-4y+2z=5 y+3=6

问题描述:

3道解三元一次方程组!
(1)7x+2y-z=7 (2)9x+4y+z=10 (3)5x-3y+6z=-3
6x-y+z=7 -9x+2y+3z=-6 2x-y+3=0
4x+3y+z=9 3x-4y+2z=5 y+3=6

7x+2y-z=7 1式6x-y+z=7 2式4x+3y+z=9 3式1式+2式得到:13x+y=14 4式1式+3式得到:11x+5y=16 5式5式-4式*5得到:11x+5y-65x-5y=16-70-54x=-54x=1 带入4式得到:13+y=14y=1带入2式得到:6-1+z=7z=2解得:x=1 y=1 z=29x...