解方程。

X-0.25=1/4    X/4=30%    

4+0.7X=102    2/3X+1/2X=42

解方程_(2)-3(x)_(3)+4(x)_(4)=-5-|||-x1- 2x3+324 =-4-|||-(x)_(1)+2(x)_(2)-5(x)_(4)=1

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

用列主元消去法解方程组 ) 3(x)_(1)-(x)_(2)+4(x)_(3)=1 -(x)_(1)+2(x)_(2)-9(x)_(3)=0 -4(x)_(1

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

解方程。x+25%x=(4)/(3)71x-25x=13.8(7)/(9)x=(2)/(3)解方程。$x+25%x=\frac{4}{3}$71x-25x=13

例4 解方程-|||-^2-6x+9=0.

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)_(

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

求解下列齐次线性方程组-|||- ) (x)_(1)+2(x)_(2)-(x)_(3)+(x)_(4)=1 2(x)_(1)+4(x)_(2)-2(x)_(3

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)_(