(後只人季 上三角矩阵性质:设A、B为上三角矩阵: B 0 (1)A±B,kA也是上三角矩阵 a,±b 11 十 A±B= 22 22 a.士b11 11 22 22 * * , 0 0 nn nn a b a b A B a b             = =             11 11 22 22 * 0 nn nn a b a b A B a b          =       