1.1*2*3+2*3*4+.+100*101*102= 2.1*2*3*4+2*3*4*5+.+n(n+1)(n+2)
证明:1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+)
如果正整数n使得[n/2]+[n/3]+[n/4]+[n/5]+[n/6]=69,则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
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
如果正整数n使得[n/2]+[n/3]+[n/4]+[n/5]+[n/6]=69,则n为( ).([ n ]表示不超过n
lim 9^n+4^n+2/5^n-3^2n-1 n趋于无穷大时
证明(1+2/n)^n>5-2/n(n属于N+,n>=3)
一道数列求和题1/2n+3/4n+5/8n+...+(2n-1)/n*2^n
急1)C(n,0)+2C(n,1)+3C(n,2)+4C(n,3) +...+(n+1)C(n,n)=(n+2)*2^(
已知递推公式f(n)=(n-1)(n-2)[f(n-2)+f(n-3)+(n-3)*f(n-4)] (n>4)求通项公式
用数学归纳法证明:1×2×3+2×3×4+…+n×(n+1)×(n+2)=n(n+1)(n+2)(n+3)4(n∈N