1\1*3+1\2*4+1\3*5+...+1\n(n+2)
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
化简:1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4)
(n+1)(n+2)/1 +(n+2)(n+3)/1 +(n+3)(n+4)/1
证明(1+2/n)^n>5-2/n(n属于N+,n>=3)
lim 9^n+4^n+2/5^n-3^2n-1 n趋于无穷大时
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
化简(n+1)(n+2)(n+3)
一道数列求和题1/2n+3/4n+5/8n+...+(2n-1)/n*2^n
证明:1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+)
计算:n(n+1)(n+2)(n+3)+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)+··
lim[(n+3)/(n+1))]^(n-2) 【n无穷大】