9.设向量组α1,α 2,α3与向量组β1 β2,β3有如下关系:-|||-(beta )_(1)=(alpha )_(2)+(alpha )_(3) (beta )_(2)=(alpha )_(1)+(alpha )_(3) (beta )_(3)=(alpha )_(1)+(alpha )_(2),-|||-证明:向量组α1,α2 α3与向量组β1,β 2,β3等价.