a1=3.a(n+1)=2an-1,证明数列an-1是等比数列

a1=3.a(n+1)=2an-1,证明数列an-1是等比数列
a1=3.a(n+1)=2an-1,证明数列an-1是等比数列

a1=3.a(n+1)=2an-1,证明数列an-1是等比数列
因为a1=3 a(n+1)=2an-1
所以a(n+1)-1=2an-1-1=2(an-1)
即(a(n+1)-1)/(an-1)=2,且a1-1=3-1=2≠0
所以数列{an-1}是等比数列,首项为2,公比为2