题目

Tony comes home from school. He wants to play football, but he has a lot of homework.“Hello, Tony!” says his mother. “How is school today?”“Fine. But I have a lot of homework,” Tony says. “I’d like a bottle of milk.”“Sorry, there isn’t any. You can eat some cakes. But please don’t eat too many. We’re going to have supper.”Tony eats some cakes. Then he sits at the table. He begins to do his homework.Mother goes to the shop. She buys some milk and some bread. There are not many people in the shop. She comes home soon.Tony is still doing his homework.“Tony, you3．已知集合P={x∈R|x2+ax+4=0}（1）若P={2}，求实数a的值；（2）若{1}?P，求实数a的值．