设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}...设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}的通项
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![设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}...设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}的通项](/uploads/image/z/1132004-20-4.jpg?t=%E8%AE%BE%E6%95%B0%E5%88%97%7Ban%7D%E6%98%AF%E5%85%AC%E5%B7%AE%E4%B8%BAd%EF%BC%88d%EF%BC%9E0%EF%BC%89%E7%9A%84%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%2CSn%E4%B8%BA%7Ban%7D%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8C%2C%E5%B7%B2%E7%9F%A5S4%3D24%2Ca2%E4%B9%98a3%3D35%2C%EF%BC%881%EF%BC%89%E6%B1%82%E6%95%B0%E5%88%97%7Ban%7D...%E8%AE%BE%E6%95%B0%E5%88%97%7Ban%7D%E6%98%AF%E5%85%AC%E5%B7%AE%E4%B8%BAd%EF%BC%88d%EF%BC%9E0%EF%BC%89%E7%9A%84%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%2CSn%E4%B8%BA%7Ban%7D%E7%9A%84%E5%89%8Dn%E9%A1%B9%E5%92%8C%2C%E5%B7%B2%E7%9F%A5S4%3D24%2Ca2%E4%B9%98a3%3D35%2C%EF%BC%881%EF%BC%89%E6%B1%82%E6%95%B0%E5%88%97%7Ban%7D%E7%9A%84%E9%80%9A%E9%A1%B9)
设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}...设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}的通项
设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}...
设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,
(1)求数列{an}的通项公式
(2)若bn=1/anan+1,且{bn}的前项和为Tn,求Tn
设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}...设数列{an}是公差为d(d>0)的等差数列,Sn为{an}的前n项和,已知S4=24,a2乘a3=35,(1)求数列{an}的通项
(1)S4=2(a2+a3),a2+a3=12
a2a3=35
t^2-12t+35=0
a2=5,a3=7
an=2n+1
(2)1/an(an+1)=(1/2)[1/(2n+1)-1/(2n+3)]
Tn=1/2(1/3-1/5+1/5-1/7+...-1/(2n+1)+1/(2n+1)-1/(2n+3))
=n/[3(2n+3)]
(1)S4=2(a2+a3),a2+a3=12
a2a3=35
t^2-12t+35=0
a2=5,a3=7
an=2n+1
(2)1/an(an+1)=(1/2)[1/(2n+1)-1/(2n+3)]
Tn=1/2(1/3-1/5+1/5-1/7+...-1/(2n+1)+1/(2n+1)-1/(2n+3))
=n/[3(2n+3)]