(1)∵ x+1 x?2 ≥0,∴ (x+1)(x?2)≥0 x?2≠0 ,解得x>2或x≤-1,∴函数f(x)= x+1 x?2 的定义域A={x|x≤-1或x>2};∵(x-a)(x-a-1)>0,且a+1>a,∴x>a+1,或x<a,∴函数g(x)=lg[(x-a)(x-a-1)]的定义域B={x|x<a或x>a+1}.(2)∵A∪B=B,∴A?B,∴ a>?1 a+1≤2 ,解得-1<a≤1.