Due to the bad weather, cotton yield poer mu is very low this year.

由于天气不好，今年棉花亩产量很低。

And each began cohabitating with humans at different times in our evolutionary history. For example, " Mus musculus domesticus."

在我们进化史不同时期，每种老鼠都开始了与类共存生活。比如, “家鼠。”

" Mus musculus domesticus" .It began raiding human pantries around 12,000 years ago.

“Mus musculus domesticus”。大约在 12,000 年前，它开始袭击类储藏室。

" Now me mus tuddy my lessin, " went on the funny little thing.

“现在我必须好好学习， ” 那个有趣小东西继续说道。

We learned the population mean was that mu letter.

我们了解到口均值是那个 mu 字母。

So minus mu K so the force of friction--- I'll just put force of friction.

所去 mu K 所摩擦力 --- 我只输入摩擦力。

The force of friction is always mu K FN.

摩擦力始终为 mu K FN。

So pi mu is what we're working on.

所π是我们正在研究东西。

And then the last term is minus mu times minus mu, which is plus mu squared.

然后最后一项是 mu 乘 mu，即加 mu 平方。

One mu equals roughly 0.067 hectares.

一亩约等于 0. 067 公顷。

" mu" " k" times " Fn" and the " mu" " k"

" mu" " k" 乘 " Fn" 并且 " mu" " k" 将是 0.

Times mu squared times the sum from i equals 1 to n.

乘 mu 平方乘 i 等于 1 到 n 总和。

So the mu squared term just gets factorized out.

所 mu 平方项刚好被分解了。

And actually, we could have just left the mu squared there.

实际上，我们本可将 mu 平方留在那里。

I've got a mu squared term in here, and I've got two things that go in there.

我这里有一个 mu 平方项，我有两样东西。

I'm interested in understanding this as a function of mu.

我有兴趣将其理解为 mu 函数。

And let's see, minus 2 times mu-- sorry, that mu doesn't look good.

让我们看看，去 2 乘 mu-- 抱歉，mu 看起来不太好。

So this is the Greek letter mu, and we put this k here for kinetic, or we can kind of say moving friction.

k表示" 动" (kinetic)该系数等于摩擦力大小。

Similarly, the expected value for  our sum of size 3 is 3 times mu and so on and so forth.

同样，大小 3 总和预期值为 mu 3 倍，依此类推。

And so, if I wanted to learn mu, all I need to know is X bar.

所, 如果我想学习mu, 我所需要知道就是X bar。