函数是高中数学的重要内容,也是高考考查的重点内容.很多数学问题,在求解时通常需要关注函数的概念、结构和性质,才能获取破题秘诀,达到化解难点、提升能力的目的.1.关注概念,回归本质好入题例1(1)(2008年天津文)设a>1,若对任意的x∈[a,2a],都有y∈[a,a~2]满足方程log_a x+log_a y=3,这时a的取值的集合为; Function is an important part of high school mathematics and also a key content of college entrance examination.Many mathematics problems usually need to pay attention to the concept, structure and nature of the function in order to get the secret of solving the problem, to solve the difficulties and improve the ability. (1) (Tianjin, 2008) Let a> 1, if for any x∈ [a, 2a], there exists y∈ [a, a ~ 2] which satisfies the equation log_a x + log_a y = 3, then a set of values ​​for;