题目

 When was the last time you had fun with your parents? Your parents are all busy during working days; during the weekends, you may want to hang out with them but they may have to work extra hours. This is not uncommon. In China, both of the parents have their jobs. Most of the parents try their best to offer their children comfortable circumstances, but they seldom have time to stay with their children. A recent survey done in the US found that more than half of American parents spend less than three hours having fun with their children each week. As the Daily Mail noted: Families ar设函数f（x）=x2-ax+a+3，g（x）=x-a．若不存在x0∈R，使得f（x0）＜0与g（x0）＜0同时成立，则实数a的取值范围是[-3，6][-3，6]．