i have the answer to a question that we've all asked. the question is, why is it that the letter x represents the unknown? now i know we learned that in math class, but now it's everywhere in the culture -- the x prize, the x-files, project x, tedx. where'd that come from?
about six years ago i decided that i would learn arabic, which turns out to be a supremely logical language. to write a word or a phrase or a sentence in arabic is like crafting an equation, because every part is extremely precise and carries a lot of information. that's one of the reasons so much of what we've come to think of as western science and mathematics and engineering was really worked out in the first few centuries of the common era by the persians and the arabs and the turks.
this includes the little system in arabic called al-jebra. and al-jebr roughly translates to “the system for reconciling disparate parts.“ al-jebr finally came into english as algebra. one example among many.
the arabic texts containing this mathematical wisdom finally made their way to europe -- which is to say spain -- in the 11th and 12th centuries. and when they arrived there was tremendous interest in translating this wisdom into a european language.
but there were problems. one problem is there are some sounds in arabic that just don't make it through a european voice box without lots of practice. trust me on that one. also, those very sounds tend not to be represented by the characters that are available in european languages.
here's one of the culprits. this is the letter sheen, and it makes the sound we think of as sh -- “sh.“ it's also the very first letter of the word shalan, which means “something“ just like the the english word “something“ -- some undefined, unknown thing.
now in arabic, we can make this definite by adding the definite article “al.“ so this is al-shalan -- the unknown thing. and this is a word that appears throughout early mathematics, such as this 10th century derivation of proofs.
the problem for the medieval spanish scholars who were tasked with translating this material is that the letter sheen and the word shalan can't be rendered into spanish because spanish doesn't have that sh, that “sh“ sound. so by convention, they created a rule in which they borrowed the ck sound, “ck“ sound, from the classical greek in the form of the letter kai.
later when this material was translated into a common european language, which is to say latin, they simply replaced the greek kai with the latin x. and once that happened, once this material was in latin, it formed the basis for mathematics textbooks for almost 600 years.
but now we have the answer to our question. why is it that x is the unknown? x is the unknown because you can't say “sh“ in spanish. (laughter) and i thought that was worth sharing.
(applause)
Since I was a little child, I had a dream that I wanted to be a doctor.When I was little, I watched many TV series and movies about doctors. I thoughtthey were so great. Therefore, I made up my mind to be a doctor. In my opinion,doctor is the people who can help patience get out of sickness and pain.I wantto be the person who can help others. However, being a doctor needs so muchprofessional knowledge and there is a long way to go. So I have to try my beston my study and go to a good college.
As we all know, "Failure is the mother of success." But few people can really understand what the saying means.
In the world, I am sure that no one dare say he hasn't met any trouble all his life. So we must face failure. In fact, failure is not fearful, but important thing is how to face it correctly. Facing failure, people will never take their fate lying down. They will try their best to work harder and harder until at last they succeed.
Not being courageous to face setbacks, people have no chance to enjoy the pleasure of success. So they have nothing to do but feel sad and empty all day and all night. In fact, they lose the chance of success themselves.
My friend, whenever in trouble, please remember, "Failure is the mother of success."
我们都知道，“失败是成功之母”。但很少有人能真正理解这句话的意思。
在这个世界上，我相信没有人敢说他在生活中还没有遇到任何麻烦，所以我们必须面对失败。事实上，失败并不可怕，重要的是如何正确面对它。敢于面对失败，人们将不再被命运打倒。他们越来越努力工作直到最后成功。
不敢面对挫折，人们也就没有机会享受成功的喜悦。他们会无所事事而感到伤心和整天整夜的空虚。事实上，他们丧失了成功的机会。
我的朋友，无论何时你遇到了困难，请记住：“失败是成功之母。”