已知f(x)=log m x(m为常数,m>0且m≠1),设f(a 1 ),f(a 2 ),…,f(a n )(n∈N + )是首项为4,公差为2的等差数列. (1)求证:数列{a n }是等比数列; (2)若b n =a n f(a n ),记数列{b n }的前n项和为S n ,当 m= 2 时,求S n ; (3)若c n =a n lga n ,问是否存在实数m,使得{c n }中每一项恒小于它后面的项?若存在,求出实数m的取值范围.
【简答题】A.Because the furniture they get in this way is better in quality. B.Because it saves them a lot of money. C.Because it saves them much trouble and money. D.Because they can get better quality furnitu...