(2)+(3)得
5x+3y=10 (4)
(4)-(1)得
3x=5
∴x=5/3
把x=5/3代入(1)得
10/3+3y=5
y=5/9
把x=5/3代入(3)得
4z+25/3=7
z=-1/3
∴方程组的解是
x=5/3
y=5/9
z=-1/3