2^n/n*(n+1)
若n为正整数,求1/n(n+1)+1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4)+.+1/
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
紧急:求 lim n*sin(π(n^2+2)^0.5)*(-1)^n,n趋向无穷大;
化简整式.六分之一× [ 3n×(n+1)+2n×(n+1)×(n-1)]
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
n分之1+n分之2+n分之3+……n分之n-1=
化简(n+1)(n+2)(n+3)
n(n+1)(n+2)数列求和
n(n+1)(n+2)等于多少?
设f(n)=1/(n+1)+1/(n+2)+……+1/(2n) (n∈N新),那么f(n+1)-f(n)等于(1/(2n
化简[n^2+(n+1)^2]/n(n+1) 化简额