设等比数列{an}的公比为q,前n项和为Sn,且a1>0,若s2>2a3,则q的取值范围是
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![设等比数列{an}的公比为q,前n项和为Sn,且a1>0,若s2>2a3,则q的取值范围是](/uploads/image/z/15231269-29-9.jpg?t=%E8%AE%BE%E7%AD%89%E6%AF%94%E6%95%B0%E5%88%97%7Ban%7D%E7%9A%84%E5%85%AC%E6%AF%94%E4%B8%BAq%2C%E5%89%8Dn%E9%A1%B9%E5%92%8C%E4%B8%BASn%2C%E4%B8%94a1%3E0%2C%E8%8B%A5s2%3E2a3%2C%E5%88%99q%E7%9A%84%E5%8F%96%E5%80%BC%E8%8C%83%E5%9B%B4%E6%98%AF)
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设等比数列{an}的公比为q,前n项和为Sn,且a1>0,若s2>2a3,则q的取值范围是
设等比数列{an}的公比为q,前n项和为Sn,且a1>0,若s2>2a3,则q的取值范围是
设等比数列{an}的公比为q,前n项和为Sn,且a1>0,若s2>2a3,则q的取值范围是
a1+a1q>2a1q^2
2q^2-q-1
s2>2a3
即a1+a2>a3
a1+a1q>a1q^2
因为a1>0
所以q^2-q-1<0
得q的范围为((1-√5)/2,0)∪(0,(1+√5)/2)