x+y-2z=5 2x-y-z=4 3x+y-3z=10;分别求x、y、z的值.

问题描述:

x+y-2z=5 2x-y-z=4 3x+y-3z=10;分别求x、y、z的值.

x+y-2z=5 (1)
2x-y-z=4 (2)
3x+y-3z=10 (3)
(1)+(2)
3x-3z=9
x-z=3 (4)
(2)+(3)
5x-4z=14 (5)
(5)-(4)×4
5x-4x=14-12
所以
x=2
z=x-3=-1
y=5+2z-x=1我明白了!!