题目

已知函数的图象与直线恰有三个公共点，这三个点的横坐标从小到大分别为，则________. 答案：【答案】【解析】求解直线 恒过定点（，0），k＞0恰有三个公共点，其直线必过f（x）的对称点（，0），其它两点是直线与f（x）的切点，那么x1+x3=，由导函数几何意义：f′（2x）=-sin2=k，再由切线方程即可求出.由题意，直线可得y=k(x-)恒过定点（，0），即x2=∵k＞0恰有三个公共点，其直线必与（x）的综合填空。     My name is Mike Green. I come from England. I study in a middle school in London. My father works in a school. My mother doesn't work. She stays at home and does the housework. I go to school five days a week. I like swimming and listening to popular music. I don't have much homework to do. After school, I help my mother do the housework. I love my father and mother. They're very kind to me.      Mike is an 1_____ boy. He is a middle school 2_____. His father is a 3_____, His mother 4_____ go to work. John doesn't go to school on 5_____ or 6_____. He 7_____ swimming. He 8_____ have much homework to do. He often 9_____ his mother do the housework. He is a 10_____ child.