The mathematical secrets of Pascal’s triangle - Wajdi Mohamed Ratemi

Matematičke tajne Pascalovog trokuta - Wajdi Mohamed Ratemi

3,056,876 views

2015-09-15 ・ TED-Ed


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The mathematical secrets of Pascal’s triangle - Wajdi Mohamed Ratemi

Matematičke tajne Pascalovog trokuta - Wajdi Mohamed Ratemi

3,056,876 views ・ 2015-09-15

TED-Ed


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Prevoditelj: Tamara Rabuzin Recezent: Ivan Stamenković
00:07
This may look like a neatly arranged stack of numbers,
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Ovo možda izgleda samo kao uredno složen stog brojeva,
00:11
but it's actually a mathematical treasure trove.
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ali zapravo je matematičko skriveno blago.
00:14
Indian mathematicians called it the Staircase of Mount Meru.
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Indijski matematičari zvali su ga Stepenice planine Meru.
00:18
In Iran, it's the Khayyam Triangle.
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U Iranu, to je Khayyamov trokut,
00:21
And in China, it's Yang Hui's Triangle.
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a u Kini, Yang Huijev trokut.
00:23
To much of the Western world, it's known as Pascal's Triangle
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Većini zapadnog svijeta poznat je kao Pascalov trokut
00:28
after French mathematician Blaise Pascal,
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po francukom matematičaru Blaiseu Pascalu,
00:31
which seems a bit unfair since he was clearly late to the party,
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što je ipak malo nepravedno, jer očito nije izmislio ništa novo,
00:35
but he still had a lot to contribute.
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ali ipak je i on dao svoj doprinos.
00:37
So what is it about this that has so intrigued mathematicians the world over?
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Ali zašto je toliko zaokupljao matematičare diljem svijeta?
00:42
In short, it's full of patterns and secrets.
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Ukratko, pun je obrazaca i tajni.
00:46
First and foremost, there's the pattern that generates it.
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Prvo i najvažnije, uzorak koji ga generira.
00:49
Start with one and imagine invisible zeros on either side of it.
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Počnite s jedinicom i zamislite nevidljive nule s obje strane jedinice.
00:54
Add them together in pairs, and you'll generate the next row.
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Zbrojite po dva broja, i generirat ćete slijedeći red.
00:58
Now, do that again and again.
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Sada ponavljajte postupak.
01:02
Keep going and you'll wind up with something like this,
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Nastavite i dobit ćete nešto poput ovog,
01:05
though really Pascal's Triangle goes on infinitely.
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iako se Pascalov trokut nastavlja u beskonačnost.
01:09
Now, each row corresponds to what's called the coefficients of a binomial expansion
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Svaki red odgovara nečemu naziva binomni koeficijenti
01:14
of the form (x+y)^n,
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raspisa (x+y)^n,
01:18
where n is the number of the row,
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gdje je n broj reda,
01:21
and we start counting from zero.
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ako krećemo brojiti od nule.
01:23
So if you make n=2 and expand it,
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Na primjer ako raspišemo izraz za n=2,
01:26
you get (x^2) + 2xy + (y^2).
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dobit ćemo (x^2)+2xy+(y^2).
01:31
The coefficients, or numbers in front of the variables,
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Koeficijenti, ili brojevi ispred varijabli,
01:34
are the same as the numbers in that row of Pascal's Triangle.
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jednaki su brojevima u odgovarajućem redu Pascalovog trokuta.
01:38
You'll see the same thing with n=3, which expands to this.
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Isto možete vidjeti i za n=3, što se raspisuje ovako.
01:43
So the triangle is a quick and easy way to look up all of these coefficients.
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Trokut je dakle brz i jednostavan način za pronalaženje koeficijenata.
01:48
But there's much more.
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Ali to nije sve.
01:50
For example, add up the numbers in each row,
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Na primjer, zbrojite brojeve u svakom redu,
01:52
and you'll get successive powers of two.
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i dobit ćete uzastopne potencije od dva.
01:56
Or in a given row, treat each number as part of a decimal expansion.
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Ili u bilo kojem redu, gledajte svaki broj kao dio decimalnog zapisa.
02:01
In other words, row two is (1x1) + (2x10) + (1x100).
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Drugim riječima, drugi red je (1x1) + (2x10) + (1x100).
02:07
You get 121, which is 11^2.
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Rješenje je 121, što je 11^2.
02:12
And take a look at what happens when you do the same thing to row six.
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Pogledajte što će se dogoditi kada napravite isto u šestom redu.
02:15
It adds up to 1,771,561, which is 11^6, and so on.
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Rješenje je 1 771 561, što je 11^6, i tako dalje.
02:25
There are also geometric applications.
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Postoje i geometrijske primjene.
02:27
Look at the diagonals.
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Pogledajte dijagonale.
02:29
The first two aren't very interesting: all ones, and then the positive integers,
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Prve dvije nisu posebno zanimljive: samo jedinice, a zatim pozitivni brojevi;
02:34
also known as natural numbers.
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poznatiji kao prirodni brojevi.
02:36
But the numbers in the next diagonal are called the triangular numbers
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Ali brojevi u slijedećoj dijagonali zovu se trokutasti brojevi
02:40
because if you take that many dots,
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jer ako uzmete toliko točkica,
02:42
you can stack them into equilateral triangles.
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možete ih naslagati u jednakostranične trokute.
02:46
The next diagonal has the tetrahedral numbers
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Slijedeća dijagonala ima tetraedne brojeve
02:49
because similarly, you can stack that many spheres into tetrahedra.
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jer se navedeni broj sfera može naslagati u tetraedar.
02:54
Or how about this: shade in all of the odd numbers.
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Ili primjerice: zasjenčajte sve neparne brojeve.
02:57
It doesn't look like much when the triangle's small,
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To nije posebno zanimljivo kada je trokut mali,
03:00
but if you add thousands of rows,
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ali ako se dodaje tisuće redova,
03:03
you get a fractal known as Sierpinski's Triangle.
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dobije se Sierpinskijev fraktal.
03:07
This triangle isn't just a mathematical work of art.
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Ovaj trokut nije samo matematičko umjetničko djelo.
03:10
It's also quite useful,
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On je i koristan,
03:12
especially when it comes to probability and calculations
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posebice u područjima vjerojatnosti i računanju
03:15
in the domain of combinatorics.
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u području kombinatorike.
03:18
Say you want to have five children,
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Ako primjerice želite imati petero djece
03:20
and would like to know the probability
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i želite znati koja je vjerojatnost
03:22
of having your dream family of three girls and two boys.
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da dobijete kako ste sanjali: tri djevojčice i dva dječaka.
03:26
In the binomial expansion,
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U zapisu pomoću potencije binoma,
03:28
that corresponds to girl plus boy to the fifth power.
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to odgovara djevojčici + dječaku na petu potenciju.
03:32
So we look at the row five,
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Pa pogledajmo peti red,
03:33
where the first number corresponds to five girls,
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gdje prvi broj odgovara pet djevojčica,
03:37
and the last corresponds to five boys.
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a posljednji pet dječaka.
03:39
The third number is what we're looking for.
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Mi tražimo treći broj.
03:42
Ten out of the sum of all the possibilities in the row.
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Deset kroz zbroj svih mogućnosti u tom redu.
03:46
so 10/32, or 31.25%.
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pa je to, 10/32, ili 31.25%.
03:51
Or, if you're randomly picking a five-player basketball team
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Ili, ako nasumično izabirete peteročlanu košarkašku momčad
03:55
out of a group of twelve friends,
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iz skupine od 12 prijatelja,
03:57
how many possible groups of five are there?
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koliko mogućih grupa od pet osoba postoji?
04:00
In combinatoric terms, this problem would be phrased as twelve choose five,
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Jezikom kombinatorike, ovaj problem izražen je kao 12 povrh 5,
04:05
and could be calculated with this formula,
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i računa se pomoću ove formule,
04:07
or you could just look at the sixth element of row twelve on the triangle
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ili jednostavno možete pogledati šesti element dvanaestog reda u trokutu
04:11
and get your answer.
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i dobit ćete odgovor.
04:13
The patterns in Pascal's Triangle
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Obrasci u Pascalovom trokutu
04:15
are a testament to the elegantly interwoven fabric of mathematics.
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dokaz su elegantnog ispreplitanja djelova matematike.
04:19
And it's still revealing fresh secrets to this day.
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Sve njegove tajne još nisu otkrivene.
04:23
For example, mathematicians recently discovered a way to expand it
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Na primjer, matematičari su nedavno otkrili način kako ga proširiti
04:27
to these kinds of polynomials.
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na ovu vrstu polinoma.
04:30
What might we find next?
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Što ćemo naći slijedeće?
04:31
Well, that's up to you.
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To je na vama.
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