2n+(n-1)+(n-2)+...+3+2+1化简得多少?

2n+(n-1)+(n-2)+...+3+2+1化简得多少? 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 1+3+5+7+9+…+(2n-1)=?得多少? 2^n/n*(n+1) [3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简 化简(n+1)(n+2)(n+3) 计算：n(n+1)(n+2)(n+3)+1 lim[(n+3)/(n+1))]^(n-2) 【n无穷大】 (1/(n^2 n 1 ) 2/(n^2 n 2) 3/(n^2 n 3) ……n/(n^2 n n)) 当N越于无穷大 当n为正偶数,求证n/(n-1)+n(n-2)/(n-1)(n-3)+...+n(n-2).2/(n-1)(n-3).. 1 + (n + 1) + n*(n + 1) + n*n + (n + 1) + 1 = 2n^2 + 3n + 3 9n^2+3n-2怎样化简为(3n-1)(3n+2)