2.设alpha_(1)=(1,0,2,3)^T,alpha_(2)=(1,1,3,5)^T,alpha_(3)=(1,-1,a,1)^T,beta=(1,b,4,7)^T,问：当a,b为何值时，β不能由alpha_(1),alpha_(2),alpha_(3)线性表示？a,b为何值时，β可由alpha_(1),alpha_(2),alpha_(3)线性表示？写出表达式.

8.求向量组 alpha_(1)=(1,-1,5,-1)^T, alpha_(2)=(1,1,-2,3)^T, alpha_(3)=(3,-1,8,1)^T,

7.设alpha_(1),alpha_(2),alpha_(3),beta_(1),beta_(2)均为4维列向量，矩阵A=(alpha_(1),alpha_(

13.试用初等变换法，(1)求向量组alpha_(1)=(1,4,1,0)^T,alpha_(2)=(2,1,-1,-3)^T,alpha_(3)=(1,0,-

8 填空若beta=(1,2,t)^T可由向量组alpha_(1)=(2,1,1)^T,alpha_(2)=(-1,2,7)^T,alpha_(3)=(1,-1

设向量组alpha_(1)=(1,-1,2,4),alpha_(2)=(0,3,1,2),alpha_(3)=(3,0,7,14),alpha_(4)=(1,-

2.判断向量组alpha_(1)=(1,2,-1,3)^T, alpha_(2)=(2,1,0,-1)^T, alpha_(3)=(3,3,-1,2)^T是否线

已知向量组 alpha_(1)=(t,2,1)^T,alpha_(2)=(2,t,0)^T,alpha_(3)=(1,-1,1)^T线性相关，则t的值为（）A.

已知alpha_(1),alpha_(2),beta,gamma均为3维列向量，又A=(alpha_(1),alpha_(2),beta)，B=(alpha_(

4.(判断题) 向量组满足 beta_(1)=alpha_(1), beta_(2)=alpha_(1)+alpha_(2), beta_(3)=alpha_(

(9)设向量组alpha_(1)=(1,3,6,2)^T,alpha_(2)=(2,1,2,-1)^T,alpha_(3)=(1,-1,a,-2)^T线性相关，