题目

方程|x2－2x|＝a2＋1(a＞0)的解的个数是( )． A．1                B．2                C．3                D．4 答案：B解析 (数形结合法)∵a＞0，∴a2＋1＞1.而y＝|x2－2x|的图象如图，∴y＝|x2－2x|的图象与y＝a2＋1的图象总有两个交点．∴方程有两解．--You're always studying hard!-- Because I want to get good grades and I don't want to______ my parents.A. surprise B. disappoint C. praise D. suppose