解:(1) 由 ∴ ∴··································································· 4分 (2) ∵ a > 1 ∴在[0,1]上递增 ∴, ∴ 即 ∴······························································································· 8分 (3) 在y轴上的截距为
要使的图象不过第二象限, 只需 ∴ ∴ 因此,a的取值范围为····································································· 12分 |