⑩天掌 Teaching Plan on Advanced Mathematics 设xn=(1+ =1+ n1.(n-1)1 (n-1)…(n-n+1)1 1!n2 1+1+(1--)+…+(1--)(1--)…(1 2! n 类似地, 1+1+,(1 +1 2 n-1 +,(1 n n+1 +2 n+1 2 十 n n n+2 nTianjin Polytechnic University Teaching Plan on Advanced Mathematics n n n x ) 1 设 = (1 + ). 1 ) (1 2 )(1 1 (1 ! 1 ) 1 (1 2! 1 1 1 n n n n n n − = + + − ++ − −  −  + − = +  + 2 1 2! 1 ( 1) 1! 1 n n n n n n n n n n n n 1 ! ( 1) ( 1)  − − + +  ). 1 ) (1 2 2 )(1 1 1 (1 ( 1)! 1 ) 1 1 ) (1 2 2 )(1 1 1 (1 ! 1 ) 1 1 (1 2! 1 1 1 1 + − + − + − + + + − − + − + + − + + + = + + − n n n n n n n n n n n xn    类似地