So I differentiated this object, this is my first derivative and I set it equal to 0 Now in a second I'm going to work with that, but I want to make sure i'm going to find a maximum and not a minimum, so how do I make sure I'm finding a maximum and not a minimum?

这样我就对它求出导数了,这是一阶导数,令它等于0,一会我们就要计算了,但我先确定一下是最大值还是最小值,我怎么确定是最大值还是最小值呢

耶鲁公开课 - 博弈论课程节选

The only place q1 appears here is here, so when I differentiate again I'm going to get -2b and sure enough that's negative, which is what I wanted to know, just to check that when I'm finding this thing, I'm finding a maximum and not a minimum.

只有这一处有q1,因此二阶导数是-2b,它肯定是个负数了,这正是我们想得到的结果,这就验证了我们刚才得出的,是最大值而不是最小值

耶鲁公开课 - 博弈论课程节选

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