设集合A={x|x2-3x+2=0},B={x|x2+2(a+1)x+(a2-5)=0
①若A∩B={2},求实数a的值
②若A∪B=A,求实数a的取值范围
③若U=R,A∪(CuB)=A,求实数A的取值范围