1/1×3+1/3×5+1/5×7+···+1/(2n-1)（2n+1）

已知888个连续正整数之和:n+(n+1)+(n+2)+(n+3)+(n+4)+(n+5)+(n+6)+(n+7)+·· 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 证明(1+2/n)^n>5-2/n（n属于N+,n>=3) 用数学归纳法证明“(n+1)(n+2)…(n+n)=2^n·1·3·5…(2n-1)(n∈N*)”时,从n=k到n=k+ 1+3+5+7+9+···+(2n-5)+(2n-3)+(2n-1)+(2n+1) 一道数列求和题1/2n+3/4n+5/8n+...+（2n-1）/n*2^n [3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简 证明：（2n!)/2^n*n!=1*3*5···（2n-1） 化简(n+1)(n+2)(n+3) lim 9^n+4^n+2/5^n-3^2n-1 n趋于无穷大时 2^n/n*(n+1) lim[n/(n^2+1^2)+n/(n2+2^2)+···n/(n^2+n^2)] n->无穷大