We can use that to get information about maybe the region or about the average value of a function in that region and so on.

二重积分可以用来得到关于这个区域的某些信息，或者这个区域上的一个函数的平均值，等等。

youdao

Then there is how to find the average value of some function.

接下来是计算某些函数的均值。

youdao

What does it mean to take the average value of some function f in this region r?

在区域r上求函数f的平均值,这是什么意思？

youdao