根据短文理解，完成下列各题。
My name is Kitty. I have a very big and nice room and I have a great school things collection.
My brother's room is near my room. He is Mike. And he has a big sports collection. I have twenty erasers, ten pencils, nine rulers and eight pens in my schoolbag. My brother has two baseballs, four soccer balls and five basketballs under his bed.
处的切线方程是 
（ ）
，则对任意实数a，b，M的最小值是 （ ）