(2)lim(1+2) 定义im(1+)”=e 设xn=(1+-)” n 1 n(n =1+-·- n(n-1)…(n-n+1)1 十∴ 2! =1+1+(1-)+…+(1-)1--…(n- n! n(2) e x x x + = → ) 1 lim(1 定义 e n n n + = → ) 1 lim(1 n n n x ) 1 设 = (1 +  + − = +  + 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 )(1 1 (1 ! 1 ) 1 (1 2! 1 1 1 n n n n n n − = + + − ++ − −  −