用数学归纳法证明1+1/2^2+1/3^2+````+1/n^2

证明n=2时,左边=1+1/2^2=1+1/4右边=2-1/2=1+1/2左边1∴(k^2+k+1)/[k(k+1)^2]>1/(k+1)∴-(k^2+k+1)/[k(k+1)^2]