請問此題的解題過程???感激~?

Sol
設a=10^(logx)
loga=logx
a=x
So
1+10^log(5/3)+10^[2(log5/3)]+…+10^[(n－1)log(5/3)]
=1+log(5/3)+2log(5/3)+…+(n－1)log(5/3)
=[1+(n－1)](n－1)/2*log(5/3)
=n(n－1)(log5-log3)/2
=n(n－1)(1－0.3010-0.4771)/2
=0.11095n(n－1)>2007
134*133*0.11095=1977.35
135*134*0.11095=2007.0855
最小n=135