x1taix,.. .+alx=b a122x2+…+a2xxn=b2, as2x2+.ta srn=b 其中al=an+ay(-)=an-an1a1/a1 6=6, +6a11x1+a12x2+…+a1nxn =b1 , a 1 22 x2+…+a 1 2nxn =b 1 2 ,  a 1 s2x2+…+a 1 snxn =b 1 s . (1.2) 其中 a 1 ij =aij +a1j ( ) 11 1 a ai − = aij−ai1 a1j /a11, b 1 i =bi +b1 ( ) 11 1 a ai − = bi−ai1 b1 /a11