等差数列{an}中,Sn是其前n项和,[S2008/2008]-[S2006/2006] =2 ,公差d=
问题描述:
等差数列{an}中,Sn是其前n项和,[S2008/2008]-[S2006/2006] =2 ,公差d=
答
由于S2008/2008=2008(a1+a2008)/2*2008=1/2(a1+a2008)
S2006/2006=2006(a1+a2006)/2*2006=1/2(a1+a2006)
[S2008/2008]-[S2006/2006] =2=1/2(a2008-a2006)=d