设n∈N+,求证:1/1²+1/2²+……+1/n²≤2-1/n

设n∈N+,求证:1/1²+1/2²+……+1/n²≤2-1/n 设n∈N,n>1.求证：logn (n+1)>log(n+1) (n+2) 设n属于N,n>1,求证logn (n+1)>logn+1 (n+2) 求证1²+2²+3²+……+n²=（1/6*n（n+1）（2n+1））/n（n为 求证：1²+2²+3²+……+n²=[n(n+1)(n+2)]/6 求证Cn0Cn1+Cn1Cn2+……+Cn(n-1)Cnn=(2n)!/(n-1)!(n+1)! 2^n/n*(n+1) 当n为正偶数,求证n/(n-1)+n(n-2)/(n-1)(n-3)+...+n(n-2).2/(n-1)(n-3).. 证明不等式：(1/n)^n+(2/n)^n+(3/n)^n+.+(n/n)^n 设n为自然数,求证1/(n+1)+1/(n+2)+1/(n+3)+...+1/(3n)>4n/(4n+1) 设n为自然数,求证n+1分之1+n+2分之1+n+3分之1+...+3n分之1大于4n+1分之4n (1/(n^2 n 1 ) 2/(n^2 n 2) 3/(n^2 n 3) ……n/(n^2 n n)) 当N越于无穷大