1*2+3*5+5*8+...+(2N-1)(3N-1)
证明(1+2/n)^n>5-2/n(n属于N+,n>=3)
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
一道数列求和题1/2n+3/4n+5/8n+...+(2n-1)/n*2^n
lim 9^n+4^n+2/5^n-3^2n-1 n趋于无穷大时
lim(3^2n+5^n)/(1+9^n)
M=(N-1)×1+(N-2)×2+(N-3)×4+(N-4)×8+(N-5)×16+(N-6)×32+(N-7)×64
已知Sn=2+5n+8n^2+…+(3n-1)n^n-1(n∈N*)求Sn
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
化简(n+1)(n+2)(n+3)
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)+··
计算:n(n+1)(n+2)(n+3)+1
lim[(n+3)/(n+1))]^(n-2) 【n无穷大】