其中一个是找出一个函数的极小值，极大值，这个函数的变量是相关的，这种方法称为拉格朗日乘数法。

One of them is to find the minimum of a maximum of a function when the variables are not independent, and that is the method of Lagrange multipliers.

youdao

但这种办法并不普遍，只能用于二元函数，来判断是极小值点、极大值点还是鞍点。

I should say that is for a function of two variables to try to decide whether a given critical point is a minimum, a maximum or a saddle point.

youdao

如果想知道是极大值还是极小值，那就只需用常识，或者直接比较各点的函数值？

So, if you want to know if something is a maximum or a minimum, you just have to use common sense or compare the values of a function at the various points you found. Yes?

youdao