x^2-(2a+1)x+a^2+a-2=x^2-(2a+1)x+(a+2)(a-1)=(x-a-2)(x-a+1)>0得x>a+2 或xx^2-(a^2+a)x+a^3=(x-a^2)(x-a)<0得 有两种情况(1)a^2>a 则aa-1a^2 =>a^2-a-2<0 =>-1a a(a-1)>0 a>1或a<0 得-1 (2)a^2a-1a =>a^2-a+1>0 这个式子总是成立的。所以a^2得0第二问.要使A∪B=R(1)a^2>a aa-1>=a 或a+2<=a^2 得无解。(2)a^2a+2<=a a^2<=a-1 得无解.
