设A 12 则 X21X22 Au A1X AA-1= 12 12 22 21 A1X1+412X21412+A2X2)(EO 22A121 2X2 O E 2222 E→X2 2 22A21= 0→X21=0 21 A1X11+A12X21=E→X11=41 1112+A1X 22 O→X12 11412422⎟⎟⎠⎞ ⎜⎜⎝⎛ = − 2221 1 1211 XX XX 设A 则 ⎟⎟⎠⎞ ⎜⎜⎝⎛ = − 22 1 1211 AO AA AA ⎟⎟⎠⎞ ⎜⎜⎝⎛ 2221 1211 XX XX ⎟⎟⎠⎞ ⎜⎜⎝⎛ = EO OE ⎟⎟⎠⎞ ⎜⎜⎝⎛ + + = 2122 2222 2212121121121111 XA XA XAXAXAXA 2222 = EXA 1 2222 − =⇒ AX 2122 = OXA ⇒ 21 = OX + 21121111 = EXAXA 1 1111 − =⇒ AX + 22121211 = OXAXA 1 2212 1 1112 −− −=⇒ AAAX