四、解答题(12分)求向量组 (alpha )_(1)=((1,8,0,-1))^T , (alpha )_(2)=((-2,9,-5,-3))^T --|||-(alpha )_(3)=((4,7,5,1))^T ,(alpha )_(4)=((7,6,10,3))^T , (alpha )_(5)=((3,-1,5,2))^T 的秩与一个极大线性无-|||-关组,并用这个极大线性无关组线性表出该向量组中其余的向量.