最α, β∈R^n, 则长 (|alpha ,alpha |)^(pi _{1)}^(pi _{1)}^(k_{1)}^theta (alpha ,beta )| . 的值 ()-|||-(A) geqslant 0 (B) =0 (C) leqslant 0 (D)不确

设矩阵 =((alpha )_(1),(alpha )_(2),(alpha )_(3),(beta )_(1))，=((alpha )_(1),(alpha

beta_1 = alpha_1, beta_2 = alpha_1 + alpha_2, beta_3 = alpha_1 + alpha_2 + alpha

设 alpha (alpha )_(1),(alpha )_(2),(alpha )_(3),(beta )_(1),(beta )_(2) 均为四维列向量矩阵

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

已知cosalpha=(1)/(2)，则cos(2pi-alpha)的值为A. $\frac{1}{2}$B. $-\frac{1}{2}$C. $\frac{

已知: alpha_1, alpha_2, alpha_3 线性无关，beta_1 = 2alpha_2 - alpha_3，beta_2 = -alpha_1

6.设α1,α2,α3线性无关, (beta )_(1)=a(alpha )_(1)+b(alpha )_(2) (beta )_(2)=a(alpha )_(

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_(

5.若cosalpha=-(1)/(2)且alphain((pi)/(2),pi)，则alpha=(2)/(3)pi。A. 对B. 错

8.若向量组α1,α2,α3线性无关, (beta )_(1)=(alpha )_(1)-(alpha )_(2), (beta )_(2)=(alpha )_