一、一元二次方程根的判别式及配方求极值许多物理问题中要求各物理量之间的关系以及求某个量的极大值或极小值或有极值的条件。在力学或电学习题中经常遇到这类问题,我们可以采取列一个关于某个量的一元二次方程,利用根的判别式配方求极值等来达到目的。如下例:例一:甲、乙两辆汽车行驶在一条平直公路上,甲车在乙车后面做速度为 v 的匀速运动,乙车在前做初 First, the quadratic equation of the root of the discriminant and formulation Extremum Many physical problems require the relationship between the physical quantities and seek a certain amount of maximum or minimum or extreme conditions. In mechanics or electrical problems are often encountered in such problems, we can take a column on a quantity of quadratic equations, the use of the root of the discriminant formula for the extreme value to achieve the goal. As an example: Example 1: A, B two cars driving in a straight road, a car in the back of the B speed to do a uniform speed v, B car before doing early