Asking the Teacher for Help Before the Exam
IntermediateSchool
A student visits her teacher's office after class to get help understanding a difficult math problem before an upcoming exam.
L
LinW
WeiL
老师，您现在有空吗？我想问您一道数学题。
lǎoshī, nín xiànzài yǒu kòng ma? wǒ xiǎng wèn nín yí dào shùxué tí.
Teacher, do you have time right now? I'd like to ask you a math problem.
W
有空，快进来坐吧。哪道题让你觉得难？
yǒu kòng, kuài jìnlái zuò ba. nǎ dào tí ràng nǐ juéde nán?
Sure, come in and have a seat. Which problem do you find difficult?
L
就是这道，关于函数的。我看了半天，也不知道该从哪儿下手。
jiù shì zhè dào, guānyú hánshù de. wǒ kàn le bàntiān, yě bù zhīdào gāi cóng nǎr xiàshǒu.
It's this one, about functions. I stared at it for a long time but don't know where to start.
W
别急，咱们一步一步来。你先说说，题目给了哪些已知条件？
bié jí, zánmen yí bù yí bù lái. nǐ xiān shuōshuo, tímù gěi le nǎxiē yǐzhī tiáojiàn?
Don't worry, let's take it step by step. First tell me, what given conditions does the problem provide?
L
题目告诉我们 x 和 y 的关系，还有一个最大值，可我不明白它们怎么联系起来。
tímù gàosù wǒmen x hé y de guānxì, hái yǒu yí gè zuìdàzhí, kě wǒ bù míngbái tāmen zěnme liánxì qǐlái.
The problem tells us the relationship between x and y, plus a maximum value, but I don't understand how they connect.
W
很好，你已经抓到关键了。其实要求最大值，通常可以用求导的方法。
hěn hǎo, nǐ yǐjīng zhuā dào guānjiàn le. qíshí yào qiú zuìdàzhí, tōngcháng kěyǐ yòng qiúdǎo de fāngfǎ.
Very good, you've already grasped the key point. Actually, to find the maximum, we usually use the method of taking the derivative.
L
求导？我们上周才学，我还不太熟。您能给我演示一遍吗？
qiúdǎo? wǒmen shàng zhōu cái xué, wǒ hái bú tài shú. nín néng gěi wǒ yǎnshì yí biàn ma?
Taking the derivative? We only learned it last week, I'm still not very familiar with it. Could you demonstrate it once for me?
W
没问题，你看，我们先把函数写出来，再对它求导，让导数等于零。
méi wèntí, nǐ kàn, wǒmen xiān bǎ hánshù xiě chūlái, zài duì tā qiúdǎo, ràng dǎoshù děngyú líng.
No problem. Look, we first write out the function, then take its derivative, and set the derivative equal to zero.
L
啊，我懂了！导数等于零的点，就是可能取到最大值的地方，对吧？
à, wǒ dǒng le! dǎoshù děngyú líng de diǎn, jiù shì kěnéng qǔ dào zuìdàzhí de dìfāng, duì ba?
Ah, I get it! The point where the derivative equals zero is where the maximum value might occur, right?
W
完全正确！不过别忘了，最后还得代回原来的函数，才能算出真正的最大值。
wánquán zhèngquè! búguò bié wàng le, zuìhòu hái děi dài huí yuánlái de hánshù, cái néng suàn chū zhēnzhèng de zuìdàzhí.
Exactly right! But don't forget, in the end you still have to plug it back into the original function to calculate the real maximum value.
L
太谢谢您了，老师！您这么一讲，我一下子就清楚多了，我回去再多练几道类似的题。
tài xièxie nín le, lǎoshī! nín zhème yì jiǎng, wǒ yíxiàzi jiù qīngchu duō le, wǒ huíqù zài duō liàn jǐ dào lèisì de tí.
Thank you so much, teacher! Once you explained it like that, it became much clearer all at once. I'll go back and practice a few more similar problems.
W
好，多练就对了。考试前要是还有不懂的，随时来找我。
hǎo, duō liàn jiù duì le. kǎoshì qián yàoshì hái yǒu bù dǒng de, suíshí lái zhǎo wǒ.
Good, practicing more is the way to go. If there's anything you still don't understand before the exam, come find me anytime.