(n-2)(n-3)÷2=
(n-2)(n-3)÷2=
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
1 + (n + 1) + n*(n + 1) + n*n + (n + 1) + 1 = 2n^2 + 3n + 3
证明(1+2/n)^n>5-2/n(n属于N+,n>=3)
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=
求极限Xn=n/(n^2+1)+n/(n^2+2)+n/(n^2+3)+……+n/(n^2+n),
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
若n²+3n=1,求n(n+1)(n+2)+1的值.
16n^a+4n^3+6n^2+7^n=0,求n
[3n(n+1)+n(n+1)(2n+1)]/6+n(n+2)化简