用克拉默法则求解下列线性方程组:(1)}x_(1)+2x_(2)+4x_(3)=31,5x_(1)+x_(2)+2x_(3)=29,3x_(1)-x_(2)+x_(3)=10;(2)}3x_(1)+2x_(2)+x_(3)=5,2x_(1)+3x_(2)+x_(3)=1,2x_(1)+x_(2)+3x_(3)=11;(3)}x_(1)-x_(2)+x_(3)-2x_(4)=2,2x_(1)-x_(3)+4x_(4)=4,3x_(1)+x_(2)+x_(3)=-1,x_(1)-2x_(2)+x_(3)-2x_(4)=4;(4)}2x_(1)+x_(2)-5x_(3)+x_(4)=8,x_(1)-3x_(2)-6x_(4)=9,2x_(2)-x_(3)+2x_(4)=-5,x_(1)+4x_(2)-7x_(3)+6x_(4)=0.

(1) $D = -27$，$D_1 = -81$，$D_2 = -108$，$D_3 = -135$，解得 $x_1 = 3$，$x_2 = 4$，$x_3 = 5$。 (2) $D = 12$，$D_1 = 24$，$D_2 = -24$，$D_3 = 36$，解得 $x_1 = 2$，$x_2 = -2$，$x_3 = 3$。 (3) $D = 1$，$D_1 = 2$，$D_2 = -3$，$D_3 = 4$，$D_4 = -5$，解得 $x_1 = 2$，$x_2 = -3$，$x_3 = 4$，$x_4 = -5$。 (4) $D = 1$，$D_1 = 3$，$D_2 = -4$，$D_3 = -1$，$D_4 = 1$，解得 $x_1 = 3$，$x_2 = -4$，$x_3 = -1$，$x_4 = 1$。 **答案：** \[ \boxed{ \begin{array}{ccccc} \text{(1) } & x_1 = 3, & x_2 = 4, & x_3 = 5, \\ \text{(2) } & x_1 = 2, & x_2 = -2, & x_3 = 3, \\ \text{(3) } & x_1 = 2, & x_2 = -3, & x_3 = 4, & x_4 = -5, \\ \text{(4) } & x_1 = 3, & x_2 = -4, & x_3 = -1, & x_4 = 1. \end{array} } \]