生一、二阶行列式的引入 用消元法解二元线性方程组 「a1x1+a12x2=b,(1) a2x1+a2x2=b2(2) ()×a2:a142x1+41212x2=b2 (2)an2:+a11=b 两式相减消去x2,得 上页用消元法解二元线性方程组    + = + = . , 21 1 22 2 2 11 1 12 2 1 a x a x b a x a x b (1) (2) (1) : a22 , a11a22 x1 + a12a22 x2 = b1a22 (2) : a12 , a12a21x1 + a12a22 x2 = b2a12 两式相减消去 x2，得 一、二阶行列式的引入