求证：1-1/2+1/3-1/4+……+1/(2n-1)-1/2n

求证1×2+2×3+3×4+…+n(n+1)＝13n(n+1)(n+2) 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).. 求证1/(n+1)+1/(n+2)+.+1/(3n+1)>1 [n属于N*] 求证Cn0Cn1+Cn1Cn2+……+Cn(n-1)Cnn=(2n)!/(n-1)!(n+1)! 设n∈N,n>1.求证：logn (n+1)>log(n+1) (n+2) 求证1!+2*2!+3*3!+…+n*n!=(n+1)!-1 求证:1+1/2+1/3+...+1/n>In(n+1)+n/2(n+1) (n属于N+) 数学定理证明求证2^n-1=2^n-1+2^n-2+2^n-3+.+2^n-n 求证c(n,1)+2c(n,2)+3c(n,3)+...+nc(n,n)=n2^(n-1) 求证：1*2+2*5+3*8+…+n(3n-1)=n^2(n+1) 求证：1²+2²+3²+……+n²=[n(n+1)(n+2)]/6 设n属于N,n>1,求证logn (n+1)>logn+1 (n+2)