题目

    The most exciting kind of education is also the most personal. Nothing can exceed (超越) the joy of discovering for yourself something that is important to you! It may be an idea or a bit of information you come across accidentally—or a sudden insight, fitting together pieces of information or working through a problem. Such personal encounters are the “payoff” in education. A teacher may direct you to learning and even encourage you in it—but no teacher can make the excitement or the joy happen. That's up to you.20090318已知幂函数的图象经过点（2，2），则这个幂函数的解析式为______．