行列式概念的引进 ax t a x= b ax t ax= b 22 22 11 xX 12\ 22 1221 21 a 22 O C b-a. b 211 a11d X 122 12021 1122 12°21行列式概念的引进 ⎩ ⎨ ⎧ =+ =+ 121 222 2 111 212 1 bxaxa bxaxa 2211 2112 211 121 2 2211 2112 212122 1 aaaa baba x aaaa baba x − − = − − = 21122211 2221 1211 aaaa aa aa − =