设3阶矩阵A的秩为2,矩阵P =,Q =,Q = ,Q =
设3阶矩阵A的秩为2,矩阵P =,Q =
设3阶矩阵A的秩为2,矩阵P =,Q =,若矩阵B=QAP ,则r(B)=_____________.