两等差数列{an}、{bn}的前n项和的比Sn/S’n=(5n+3)/(2n+7)求a5/b5的值

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两等差数列{an}、{bn}的前n项和的比Sn/S’n=(5n+3)/(2n+7)求a5/b5的值

两等差数列{an}、{bn}的前n项和的比Sn/S’n=(5n+3)/(2n+7)求a5/b5的值
两等差数列{an}、{bn}的前n项和的比Sn/S’n=(5n+3)/(2n+7)求a5/b5的值

两等差数列{an}、{bn}的前n项和的比Sn/S’n=(5n+3)/(2n+7)求a5/b5的值
a5/b5
=(a5+a5)/(b5+b5)
=(a1+a9)/(b1+b9)
=[(a1+a9)×9÷2]/[(b1+b9)×9÷2]
=S9/S'9
=(5×9+3)/(2×9+7)
=48/25

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