第七模块矩阵与线性方程组 §7-1行列式的概念、性质 X1+a12X2+a133 应 ,1x1+a x ta 22~2 123-3 用 31 xa 32~2 33~3 字 b. a 3 得D2=a21b2 239 31 33 a1x1+a12x2+a13x3 11 2 13 21x1+a2x2+a23x3 D=a21 22 n31x1+a32x2+a3x3=b3 3143233     + + = + + = + + = ; , , 3 1 1 3 2 2 3 3 3 3 2 1 1 2 2 2 2 3 3 2 1 1 1 1 2 2 1 3 3 1 a x a x a x b a x a x a x b a x a x a x b , 31 3 33 21 2 23 11 1 13 2 a b a a b a a b a 得 D =      + + = + + = + + = ; , , 3 1 1 3 2 2 3 3 3 3 2 1 1 2 2 2 2 3 3 2 1 1 1 1 2 2 1 3 3 1 a x a x a x b a x a x a x b a x a x a x b 31 32 33 21 22 23 11 12 13 a a a a a a a a a D =