某学生解方程3x2-x-2=0的步骤如下：解：3x2-x-2=0→x2-(1)/(3)x-(2)/(3)=0，①→x2-(1)/(3)x=(2)/(3)，②→（x-(2)/(3)）2=(2)/(3)+(4)/(9)，③→x-(2)/(3)=±(sqrt(10))/(3)，④→x1=(2+sqrt(10))/(3)，x2=(2-sqrt(10))/(3)，⑤上述解题过程中，最先发生错误的是（ ）

解方程组： ) (x)_(1)-(x)_(2)-(x)_(3)=2 2(x)_(1)-(x)_(2)-3(x)_(3)=1 3(x)_(1)+2(x)_(2)

配方法解方程：（1）x2-3x-2=0；（2）3x2-6x-1=0．配方法解方程：（1）x2-3x-2=0；（2）3x2-6x-1=0．

) (x)_(1)+3(x)_(3)geqslant 3 2(x)_(2)+2(x)_(3)geqslant 5 (x)_(1),(x)_(2),(x)_(3)

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

用克莱姆法则求解方程组 ) 2(x)_(1)-3(x)_(2)-3=0 3(x)_(1)-(x)_(2)-8=0 .用克莱姆法则求解方程组，其中是。

16.线性方程组 ) (x)_(1)+(x)_(3)=0 2(x)_(2)+(x)_(3)=0 2(x)_(1)+3(x)_(2)=0 .16.线性方程组用

用克莱姆法则求解方程组 ) (x)_(1)-(x)_(2)-(x)_(3)=-1 -2(x)_(1)+2(x)_(2)+(x)_(3)=1 2(x)_(1)-

方程组 ) (x)_(1)+(x)_(2)+(x)_(3)=1 (x)_(1)+2(x)_(2)-(x)_(3)=2 (x)_(1)+k(x)_(2)+(x)

5.线性方程组 ) (x)_(1)-(x)_(2)=(a)_(1) 2(x)_(2)-(x)_(3)=(a)_(2) (x)_(1)+(x)_(2)-(x)

已知二次型-|||-((x)_(1),(x)_(2),(x)_(3))=2({x)_(1)}^2+3({x)_(2)}^2+3({x)_(3)}^2+2a(x)