Ux=y l11x1+l12X2+·+ u1,m-2n-2+41,m-1式n-1+ uinXn y1, l22X2十…+42，n-2Xm-2+42,n-1xn-1+l2mXn=y2, un-2,n-2Xn-2 un-2.n-1Xn-1 un-2.nXn yn-2: un-1.n-1Xn-1 un-1nXn yn-1, ln,nxn=yn·