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设{an}是等差数列{bn}是各项都是正数的等比数列且a1=b1=2,a3+b5=36,a5+b3=14
求(1)数列{an}{bn}的通项公式(2)数列{an|bn}的前n项和Tn
急!!!!!!!!!!!!!!!!!!!!!!!
人气:211 ℃ 时间:2019-08-19 09:01:05
解答
a3+b5=36.Aa5+b3=14.Ba1+4d+b1q^2=142+4d+2q^2=144d+2q^2=122d+q^2=62d=6-q^2.CB-Aa5-a3+b3-b5=-222d+b1q^2-bq^4=-222d+2q^2-2q^4+22=0.D6-q^2+2q^2-2q^4+22=0-2q^4+q^2+28=02q^4-q^2-28=0(2q^2+7)(q^2-4)=0q^2=4 {b...
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