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."

在进化史不同时期，每种老鼠都开始了与人类共存生活。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，它开始袭击人类储藏室。

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

“现在必须好好学习， ” 那个有趣小东西继续说道。

We learned the population mean was that mu letter.

了解到人口均值那个 mu 字母。

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

所以减去 mu K 所以摩擦力 --- 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.

所以π正在研究东西。

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

然后最后一项减 mu 乘以减 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" 乘以 " Fn" 并且 " mu" " k" 将 0.

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

乘以 mu 平方乘以 i 等于 1 到 n 总和。

So the mu squared term just gets factorized out.

所以 mu 平方项刚好被分解了。

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

实际上，本可以将 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.

这里有一个 mu 平方项，有两样东西。

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

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.

让看看，减去 2 乘以 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.

所以, 如果想学习mu, 所需要知道就X bar。