在某些初中物理问题中,一物理量随另一物理量变化时,有时还会出现由小变大再变小,或者由大变小再变大的情况。这种情况下,该物理量就出现一个最大值或最小值,也称极大值或极小值。多数问题中的极大值或极小值是用数学中求极值的方法来求解的。常用的数学方法有配方法、不等式法 In some junior high school physics problems, when a physical quantity changes with another physical quantity, sometimes it may increase from smaller to smaller, or from larger to smaller and larger. In this case, the physical quantity has a maximum or minimum value, which is also called a maximum value or a minimum value. The maximum or minimum value in most problems is solved by using the method of extremum in mathematics. Commonly used mathematical methods include matching methods, inequality methods