(a1{a2-a12a21)x1=ba2-a12b2 类似地,消去x得 (a1a2-a12a2)x2=a1b2-ba21, 当a1a2-a12a21≠0时,方程组的解为 b1a22-a12b2x2= 11 b-b,a u11 11u22 12u21 11 22 12 21 1a12 212 2 22 12 12 2122 21 22; （a11a22 − a12a21）x1 = b1a22 − a12b2 类似地，消去x1，得 , （a11a22 − a12a21）x2 = a11b2 − b1a21 当 a11a22 − a12a21  0时， 方程组的解为 11 22 12 21 1 22 12 2 1 a a a a b a a b x − − = . 11 22 12 21 11 2 1 21 2 a a a a a b b a x − − = 21 22 11 12 2 22 1 12 a a a a b a b a = 21 22 11 12 21 2 11 1 a a a a a b a b =