中学数学求极值问题是一个很重要的问题，而求极值的方法也很多，本文主要通过举例说明用几何知识来求一类形如ｙ＝（ｘ－ａ）２＋ｂ２±（ｘ－ｃ）２＋ｄ２这类函数最值问题。 The problem of seeking the maximum value of mathematics in middle school is a very important issue, and there are many ways to seek the extreme value. In this paper, we mainly use the example of geometric knowledge to find a kind of shape such as y = (x-a) 2 + b2 ± (x-c) 2 + d2 the most value of such functions.