1/(n^2+n)=1/2[ 1/n - 1/(n+2) ] ∴Sn=1/(1^2+2)+1/(2^2+4)+1/(3^2+6)+……+1/(n^2+n),=1/2[1+1/2-1/(n+1)-1/(n+2)] =3/4-1/2[1/(n+1)+1/(n+2)] ∴limSn=3/4
若Sn=1/(1^2+2)+1/(2^2+4)+1/(3^2+6)+……+1/(n^2+n),求limSn拜托了各位
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