已知AN中,a1=2,6Sn=(an+1)(an+2),求数列An的通项公式An和Sn
已知AN中,a1=2,6Sn=(an+1)(an+2),求数列An的通项公式An和Sn
数学人气:603 ℃时间:2019-12-09 10:16:33
优质解答
6Sn=(an+1)(an+2)6Sn-1=(an-1+1)(an-1+2),相减得:6an=(an+an-1)(an-an-1)+3(an-an-1)继续化简:(an+an-1)(an-an-1-3)=0 ④是不是少了条件,an应该是正数吧? ④中:(an+an-1)不可能为0,所以:(a...
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