1*2*3*4*5*6*(n-1)*n=?
Sn=n(n+2)(n+4)的分项等于1/6[n(n+2)(n+4)(n+5)-(n-1)n(n+2)(n+4)]吗?
M=(N-1)×1+(N-2)×2+(N-3)×4+(N-4)×8+(N-5)×16+(N-6)×32+(N-7)×64
证明(1+2/n)^n>5-2/n(n属于N+,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)+··
如果正整数n使得[n/2]+[n/3]+[n/4]+[n/5]+[n/6]=69,则n=
证明:1+2C(n,1)+4C(n,2)+...+2^nC(n,n)=3^n .(n∈N+)
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简
根号(1×2×3+2×4×6+…+n×2n×3n)÷根号(1×5××10+2×10×20+…+n×5n×10n)=?
1\n(n+3)+1\(n+3)(n+6)+1\(n+6)(n+9)=1\2 n+18 n为正整数,求n的值
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
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
3n²-n=1 求6n³+7n²-5n+2014