若1/1*3+1/3*5+1/5*7+……+1/(2n-1)(2n+1)的值为17/35,求n值
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
若3n^2-n=1,求6n^3+7n^2-5n+2003的值
若n²+3n=1,求n(n+1)(n+2)+1的值.
若n为自然数,则n(2n+1)-2n(n-3)的值是7的倍数吗?
若n为正整数,求1/n(n+1)+1/(n+1)(n+2)+1/(n+2)(n+3)+1/(n+3)(n+4)+.+1/
求极限 lim n[1/(n^2+1)+1/(n^2+2^2)+……+1/(n^n+n^n)] (n趋向于无穷大,n^n
证明不等式:(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n
∑(N等于1,2,3,4..n) 5^N/N!,极限怎么求
已知m/n=5/3 求(1/m+n+1/m-n)÷1/n-n/m-n÷m+n/n的值,
已知:m/n=5/3,求(1/m+n+1/m-n)÷1/n-n/m-n÷m+n/n的值
求极限lim(x→∞)(1/n+2/n+3/n..+n/n)
1*2+2*3+3*4+4*5+…+n(n+1)(n为正整数)