用消元法解二元线性方程组 十a 12-2 n2x1+a2x2=b2(2) (1)×a2:a1a2x1+a1l2x2=ba2, (2)x 1 2u21 +a1, 12222 129 两式相减消去x2,得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