请用放缩法求证:2(√n+1)-2
求证:n^2+2n
(1) 求证:n
设n∈N,n>1.求证:logn (n+1)>log(n+1) (n+2)
求证:1/(n+1)+1/(n+2)+1/(n+3)+...+1/(3n+1)>25/24(n是正整数)
求证 1/(n+1)+1(n+2)+.+1(3n+1)>1
求证:对于自然数n有17/((3X5*2n+1)+(2*3n+1))
求证:3/2-1/n+1
求证1/(n+1)+1/(n+2)+.+1/(3n+1)>1 [n属于N*]
设n属于N,n>1,求证logn (n+1)>logn+1 (n+2)
已知 n>1且n属于N* ,求证logn(n+1)>logn+1(n+2)
求证:C(0,n)+2C(1,n)+.+(n+1)C(n,n)=2^n+2^(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)..