已知数列{an}满足a1=3,an=2-(1/an-1).求证:数列{1/an-1}是等差数列,并写出{an}的一个通项
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已知数列{an}满足a1=3,an=2-(1/an-1).求证:数列{1/an-1}是等差数列,并写出{an}的一个通项公式.
注明:n、n-1都是a的下标.
没有看明白过程.请不要粘贴.
注明:n、n-1都是a的下标.
没有看明白过程.请不要粘贴.
![已知数列{an}满足a1=3,an=2-(1/an-1).求证:数列{1/an-1}是等差数列,并写出{an}的一个通项](/uploads/image/z/19994182-70-2.jpg?t=%E5%B7%B2%E7%9F%A5%E6%95%B0%E5%88%97%7Ban%7D%E6%BB%A1%E8%B6%B3a1%3D3%2Can%3D2-%EF%BC%881%2Fan-1%EF%BC%89.%E6%B1%82%E8%AF%81%EF%BC%9A%E6%95%B0%E5%88%97%7B1%2Fan-1%7D%E6%98%AF%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%2C%E5%B9%B6%E5%86%99%E5%87%BA%7Ban%7D%E7%9A%84%E4%B8%80%E4%B8%AA%E9%80%9A%E9%A1%B9)
an=2- 1/a(n-1)
= [2a(n-1) -1]/a(n-1)
an -1 = [a(n-1) -1]/a(n-1)
1/(an-1) = a(n-1)/[a(n-1) -1]
= 1 + 1/[a(n-1) -1]
1/(an-1) - 1/[a(n-1) -1]=1
{1/( an -1) }是等差数列, d=1
1/( an -1) -1/( a1 -1) = n-1
1/( an -1) = (2n+1)/2
an = 2/(2n+1) +1
= (2n+3)/(2n+1)
= [2a(n-1) -1]/a(n-1)
an -1 = [a(n-1) -1]/a(n-1)
1/(an-1) = a(n-1)/[a(n-1) -1]
= 1 + 1/[a(n-1) -1]
1/(an-1) - 1/[a(n-1) -1]=1
{1/( an -1) }是等差数列, d=1
1/( an -1) -1/( a1 -1) = n-1
1/( an -1) = (2n+1)/2
an = 2/(2n+1) +1
= (2n+3)/(2n+1)
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