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已知等差数列{an}中,a2+a3=14,a4-a1=6.(1)求数列{an}的通项公式;(2)设等比数列{bn}满足b2=a1,b3=a3,若b6=am,求实数m的值.
题目详情
已知等差数列{an}中,a2+a3=14,a4-a1=6.
(1)求数列{an}的通项公式;
(2)设等比数列{bn}满足b2=a1,b3=a3,若b6=am,求实数m的值.
(1)求数列{an}的通项公式;
(2)设等比数列{bn}满足b2=a1,b3=a3,若b6=am,求实数m的值.
▼优质解答
答案和解析
(1)设等差数列{an}的公差为d,∵a2+a3=14,a4-a1=6.∴
,解得d=2,a1=4.∴an=4+2(n-1)=2n+2.
(2)设等比数列{bn}满足b2=a1,b3=a3,∴
,解得q=2,b1=2.
∴bn=2n.
∵b6=am,
∴26=2m+2,解得m=31.
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(2)设等比数列{bn}满足b2=a1,b3=a3,∴
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∴bn=2n.
∵b6=am,
∴26=2m+2,解得m=31.
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