1.已知方程组 ) (x)_(1)+(x)_(2)+(x)_(3)+(x)_(4)=2 3(x)_(1)+2(x)_(2)+(x)_(3)+(x)_(4)=a (x)_(2)+2(x)_(3)+2(x)_(4)=3 .有无数解，求参数 ) (x)_(1)+(x)_(2)+(x)_(3)+(x)_(4)=2 3(x)_(1)+2(x)_(2)+(x)_(3)+(x)_(4)=a (x)_(2)+2(x)_(3)+2(x)_(4)=3 .并求方程组的通解。

9.已知方程组如下-|||- ) (x)_(1)-(x)_(2)=1, -(x)_(1)+(x)_(2)=2, 2(x)_(1)-2(x)_(2)=3, -3

3.已知方程组 ) (x)_(1)+(x)_(2)+2(x)_(3)=a 3(x)_(1)-(x)_(2)-6(x)_(3)=a+2 (x)_(1)+4(x

关于方程组_(1)-2(x)_(2)+3(x)_(3)-4(x)_(4)=4 _(1)-2(x)_(2)+3(x)_(3)-4

线性方程组 ) (x)_(1)+2(x)_(2)-2(x)_(3)=1 2(x)_(1)+4(x)_(2)-4(x)_(3)=2 3(x)_(1)+6(x)_

2.解方程组 ) (x)_(1)+(x)_(2)+(x)_(3) (x)_(1)+(x)_(2)-(x)_(3)-(x)_(4)=1 5(x)_(1)+5(

3.求解线性方程组 ) (x)_(1)+2(x)_(2)-(x)_(3)+2(x)_(4)=1 2(x)_(1)+4(x)_(2)+(x)_(3)+(x)_(

1.用消元法解线性方程组.-|||- ) (x)_(1)+2(x)_(2)+(x)_(3)=3, -2(x)_(1)+(x)_(2)-(x)_(3)=-3 (

求线性方程组_(1)+(x)_(2)+(x)_(3)+(x)_(4)=0-|||-_(2)+2(x)_(3)+2(x)_(4)=1-|||-_(1)+2(x)_

设非齐次线性方程组 ) (x)_(1)+2(x)_(3)+(x)_(4)=2 (x)_(1)+(x)_(2)+(x)_(3)+4(x)_(4)=a (x)_(

4.已知非齐次线性方程组-|||- ) (x)_(1)+5(x)_(2)-(x)_(3)-(x)_(4)=-1 (x)_(1)-2(x)_(2)+(x)_(3