n阶行列式的定义 n 2 =a141+a12A2+…+anA 按第一行展开n 阶行列式的定义 21 22 11 2 2 1 1 1 2 n n n nn n a a a a a a a a a 11 12 1 A A 11 12 1 n n = + + + a a a A 1 1 1 n j j j a A = = 按第一行展开