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/sci/ - Science & Math

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File: 28 KB, 1326x381, 288.png [View same] [iqdb] [saucenao] [google]
[ERROR] No.3787575 [Reply] [Original]

/sci prides itself on being the smartest board yet i bet that it cant even solve this simple maths equation
48 /2 (9+3)
protip the answer is 288

>> No.3787582

Inb4 photo of old TI.

>> No.3787588
File: 17 KB, 250x250, ishygddt.jpg [View same] [iqdb] [saucenao] [google]
[ERROR]

> 2011
> not using fully-parenthesized prefix

>> No.3787593

48 / 2 * ( 9 + 3)
48 / (18 + 6 )
48 / ( 24)
2

lrn to BODMAS, brackets come first

>> No.3787589
File: 16 KB, 478x357, trollmaths.jpg [View same] [iqdb] [saucenao] [google]
[ERROR]

oh_look_its_this_thread_again.jpg

>> No.3787594

>>3787575
>Asks question
>Provides answer
>Calls us stupid for not providing answer
2011

>> No.3787601

>>3787589
lol what's the 2=288 and 1=9?

>> No.3787605

>see obvious troll thread
> people reply to it without saging
i seriously hope you dont do this

>> No.3787606

>>3787601
>mwf 2=288 is this thread

>> No.3787607

>>3787575
>>3787575

This is what happens when you use the stupid division sign instead of fractions.

The expression can either be:
48÷(2(9+3) = 2
or
(48÷2)(9+3) = 288

Which one is correct? We don't know.
That's why fractions are used.

>> No.3787613

>>3787607
you always solve left to right when their is no clear brackets so the second one is correct

>> No.3787614

>>3787593
Parentheses come first, then you multiply/divide from left to right.
48/2(9+3)
48/2(12)
24(12)
288

This is math for 12 year olds. Seriously.

>> No.3787619
File: 76 KB, 850x500, olittamathtroll2.jpg [View same] [iqdb] [saucenao] [google]
[ERROR]

>>3787601
tis threadis the 2=288
(for OP's problem depending on order of operations you can come out with an answer of either 2 or 288. with BIDMAS used correctly the correct answer is 288, but it is written in a purposefully confusing way.)
all the other lines are popular troll-maths answers as well. the 1 = 9 one is here:
<<<

>> No.3787624

>>3787613
You may be right, I don't know.
My point is, stop using the division sign.

>> No.3787630

>>3787619
*this thread is...

>> No.3787632

hey guys look at me im pointing out an obvious troll

>> No.3787635

>>3787624
5-3 != 5(-3)
5-3+2 != 5-(3+2)
The minus could be 'just as confusing', except it isn't, because you're wrong.

>> No.3787636

>>3787607
Actually, the precedence of operators is:

>The order of operations, or precedence, used in mathematics and many programming languages is expressed here:
> terms inside parentheses or brackets
> exponents and roots
> multiplication and division As they appear left to right
> addition and subtraction As they appear left to right

So if you write 1/2*3, you're supposed to mean (1/2)*3. Thing is, when you write 1/2n, it means 1/(2n). I think that somehow, implicit multiplication when the "*" is not written takes precedence over divisions. When it's written, it's really ambiguous, but no one really writes "*" anyway.

>> No.3787640
File: 33 KB, 230x315, 107.jpg [View same] [iqdb] [saucenao] [google]
[ERROR]

> equation
> 48 /2 (9+3)

>> No.3787644

>>3787636
Except that 1/2n = n/2. If you mean 1/(2n), then you're writing it wrong.

>> No.3787646
File: 43 KB, 800x600, calculus.jpg [View same] [iqdb] [saucenao] [google]
[ERROR]

I really don't see the issue here.

>> No.3787651

>>3787606
>>3787619
Oh, I expected something like a fallicious proof.

>> No.3787652

>>3787635
What do you mean I'm wrong, I never stated my opinion.
Also substraction isn't confusing, as it obviously just is different form of addition.
Nobody who is at least a little skilled in math could ever perceive a - b + c as a - (b + c).
This can happen with division. That's why fractions are used.

>> No.3787658

>>3787575
>doesn't understand his own paradox
>rephrasing with / instead of ÷
>doesn't realse / implies brackets

48÷2(9+3) is undefined; it's an ambiguous question. Multiplication and divison have equal priority for the order of operations, and doing 2(9+3) = (18+6) first is retarded: that counts as multiplication, not brackets.

48/2(9+3) implies 48÷(2(9+3))

guess what? You fail.

>> No.3787664

>>3787636
I learned this when I was a pre-teen. Why hasn't the rest of /sci/?

>> No.3787668

>>3787658
erm, no.
/ and ÷ are the same thing
in order of operations division and multiplication have equal priority, so without brackets you read from left to right.

>> No.3787675

>>3787644

>1/2n = n/2

½n = n/2
1/2n ≠ n/2
1/2n implies 1/(2n)

>> No.3787676

>>3787636
1/2^3=1/8=(1/2)^3 so terrible example.
2/3^2 however = 2/9 so i'm pretty sure you're a fucking retard

>> No.3787677

>>3787668
You don't understand what you're argumenting EK.
And where did people get this left to right rule anyway? I've never been taught that.

>> No.3787680

>>3787646
Welcome to the club. Most error came because poeple think with line.

>> No.3787686

>>3787668

/ ≠ ÷

/ shows the divison as a fraction and therefore implies brackets.. that's why we use that symbol.

Tbh the order of operations is arbitrary. It's all about notation; the issue with this question is just that the notation is ambiguous. We would all know the answer if someone told us what we were actually trying to work out and what each value stood for.

>> No.3787687

>>3787675
no, some asshole may have wanted to imply one divided by the quantity two times n, however he was retarded so he wrote one divided by two times n

>> No.3787708

>>3787687

a x b / c x d = (ab)/(cd)
a x b / c x d ≠ a x (b÷c) x d

>> No.3787716

>>3787686
the notation in ops pic has absolutly zero room for opinion. and / is NEVER used in math. it is a typesetting isssue, just because your dumb ass doesn't know how the order of operatiosn works, doesn't mean suddenly / has some special meaning. the / sign causes problems because it should not be used, like i said, it's a problem we have only becasue of typesetting.

>> No.3787726
File: 82 KB, 784x472, ele_info_theo.png [View same] [iqdb] [saucenao] [google]
[ERROR]

>>3787644
Image from one of the Bibles of information theory (the "Cover & Thomas, 2nd edition, page 153".
Your turn, find one well-cited article or book that uses a/bc for ac/b. No multiplication sign. I doubt you can.

>> No.3787721

>>3787708
you sir, are a dumbass

>> No.3787724

>>3787686
Nope.jpg
They're have the same meaning. Mathematics doesn't into implied meaning.

>> No.3787735

>>3787724

I'm talking notation; not mathematics itself. Notation necessarily implies things: it wouldn't be notation if it didn't...

>> No.3787737

>>3787726
Even the best authors make mistakes. Maybe it wasn't even the author that made the mistake, but the editor when he changed \frac{x}{yz} into x/yz. It's still technically wrong. Mind you, I'm not arguing that making the mistake implies that you don't know maths.

>> No.3787739

>>3787735
Except that / is just modern typesetting for the other symbol (which I don't know how to type). There is no additional meaning. Both are division. Division is division.

>> No.3787740

>>3787716
>and / is NEVER used in math

Wow, just wow. Now I'm wondering if I can find a math article that DOESN'T use "/". Probably, but that'd take time or a quite good guess.

>> No.3787746

>>3787735
implication does not happen without context.

ie
>>3787726
happens after a string of other fractions properly written. The author should have still not used the notation he did, but he was being lazy, since it is easier to typeset / instead of a horizontal bar. but NO self respecting mathemetician would EVER use the / sign without having already made it abundantly obvious what he was meaning by using horizontal division immediatly prior.

>> No.3787748

>>3787677
Your school either sucks or you didn't pay attention in maths class.

I'm gonna go with the latter.

>> No.3787749

>>3787739

Literally they both mean divison - yes - but / does conventionally imply brackets.

(It's alt-0247, for future reference, btw. Or 00F7 in hexidecimal unicode)

>> No.3787753

>>3787748

Actually, you'd be surprised: the left-to-right rule is rarely taught.

>> No.3787755

>>3787737
Then find a good damn example of the notation being used the way you think it should be used in a serious paper.

You won't find one. Why? Because while you think you know about maths, you don't know maths at research level, and you don't know how real mathematicians communicate. I found that notation in 1 book and it didn't take me long. I come across it all the time. Wolfram also uses it that way. I'm not saying that a÷b*c isn't (a÷b)*c, I'm saying that a/bc is a÷(b*c). If you don't get the difference, at least defend your opinion (because, as it's about notations, yes, it's only an opinion) with more than words, and find relevant examples in the literature.

>> No.3787760

>>3787749
Where did you get that it implies brackets? Does it imply brackets in coding? In website addresses?

It does not imply brackets in math. When math is put onto screen via a standard keyboard, it is the over/under symbol, otherwise known as division. If you want to "imply" brackets, you add brackets. They are never implied.

>> No.3787766

>>3787755
I dare YOU to find an example where your notation is used without first being written correctly. in other words, / used alone

>> No.3787768

>>3787755
a/bc is a÷(b*c)

It's not. It's A divided by B multiplied by C. It's left to right. If you want B multipied by C then A divided by that, you have to add the parentheses. That's why parentheses have their own rule all to themselves in mathematics annotation.

>> No.3787769

>>3787760
http://www.wolframalpha.com/input/?i=1%2F2n

>> No.3787771

>>3787753
I hate schools.

>> No.3787780

>>3787755
Are you saying that I don't read math papers? Then I'm not doing my job very well am I.
I occasionally see 2/3x, when they mean 2/(3x). I also see typos quite a lot. In fact the large majority of papers contain several typos, and make a notational mistake. Nobody's perfect, and I still know what they mean.
Still, people should be aware of what correct and what incorrect notation is.

>> No.3787789

>>3787769
http://www.google.com/#hl=en&sugexp=pfwc&cp=5&gs_id=q&xhr=t&q=1/2*3&pf=p&amp
;sclient=psy-ab&source=hp&pbx=1&oq=1/2*3&aq=0&aqi=h1g4&aql=f&gs_sm=&
gs_upl=&bav=on.2,or.r_gc.r_pw.&fp=2f423ba816b0f8be&biw=1080&bih=396

>> No.3787785

>>3787768
I understand what you're saying. I disagree with it. Now will you please find one occurrence of the notation used the way you think it should be used? If you cannot, it's because you're wrong. If you can, I'll admit I'm wrong and Cover&Thomas somehow didn't get any critics between their 1st and 2nd edition of the book. Unlikely, isn't it?

What's your level in maths? 2nd year of uni at most?

>> No.3787791

> implying order of operations is anything other than a custom

>> No.3787807

>>3787780
If the convention is always broken and never respected, then it's, by definition, not a convention anymore. If no one ever means uses a/bc for ac/b, then a/bc is a/(bc). It doesn't break any fundamental concept of mathematics or anything, it's just a notation, and notations mean what people understand from them.

There are incoherent or ambiguous notations that people use, but this one is not ambiguous (as everybody understands it and everybody writes it with the same meaning) and not incoherent (because, well, it's just not).

>> No.3787812

>>3787785
Alright, whatever, I concede. The / sign is used in two ways, then, and in actually annotating math, I'm wrong. However, it seems in using it on keyboards to mean the division sign, it means the division sign and that's it. So when people are using / instead of ÷, they should be using ÷ and maybe they are wrong in using /, but that doesn't mean OP's picture is 2. It's still 288.

(Also, I'm not the one who was arguing with whoever, those two going back in forth. I just came into that discussion.)

>> No.3787814

>>3787748

I don't know. I might've been taught it but I frankly don't remember, as I never needed to use it. Things such as this don't happen in university math so it just kind of disappear from memory.

>> No.3787821

>>3787789
You used a multiplication sign.

>>3787726
>No multiplication sign.

I never said anything about 1/2*n, I'm talking about 1/2n.

>> No.3787828

>>3787821
2n is 2 multiplied by n

It's implied.

>> No.3787833

>>3787812

It wasn't the same two going back and forth ha, I was in the midst at one point ;D

>>3787791
This is an important point though; I think we all need to remember that.

>> No.3787840

>>3787807
the use of the / sign was made obvious by the 3 terms correctly written that came before it. Good mathemeticians do this on occasion because they hate typesetting, and editors do it because it's prettier. You will seriously never see an expression introduced for the first time using / signs, and if you do, it will be followed by a formal notation. Seriously, / is a lazy shorthand, and it is only possible to know what ws ment from context, strictly speaking, it is very poor form to use, but even in the highest level math papers, authors make consessions for the sake of typing strokes, and aesthetics.

>> No.3787855

>>3787807
What I'm saying is, there is a shitloads of rules that a shitload of mathematicians ignore. It is still important to be aware of the rule. _Even_ if you choose to ignore it.
If you write 1/2x (to mean 1/(2x)) then you should be aware that technically, you're writing x/2. However, it might still be clearer, since a mess of parenthesis is also a bad thing. The context should clarify what you mean.
Another case is implicit definition. I understand that n is supposed to be an integer, even though you didn't define it's type, but you should be aware of the fact that it's technically wrong.

>> No.3787880

>>3787821
both forms have been flying around this discussion, either a / sign followed by a quantity with signs or with implied multiplication. and whatever the programmer decided to do with wolfram alphas editor really doesn't matter.

>> No.3787911

>>3787855
The difference with the implicit assumption that n is an integer, is that this assumption doesn't break some kind of "law" that would say that integers cannot be written "n". It if did and people kept writing n for integers and understanding it that way, it would be safe to assume that the rule isn't valid anymore and should be reformulated.

I think wolfram's rule is the rule that mathematicians use.
1) parenthesis or brackets,
2) Exponents,
3) Implicit multiplication with no sign,
4) Multiplications and divisions, whatever the symbol, left to right,
5) Additions and subtractions, left to right.


But I'll leave you to the synchronization of the CERN's clock.

>> No.3787974

From Texas Instruments:
Implied Multiplication Versus Explicit Multiplication on TI Graphing Calculators. - Knowledge Base by Texas Instruments - US and Canada
Implied multiplication has a higher priority than explicit multiplication to allow users to enter expressions, in the same manner as they would be written. For example, the TI-80, TI-81, TI-82, and TI-85 evaluate 1/2X as 1/(2*X), while other products may evaluate the same expression as 1/2*X from left to right. Without this feature, it would be necessary to group 2X in parentheses, something that is typically not done when writing the expression on paper.

This order of precedence was changed for the TI-83 family, TI-84 Plus family, TI-89 family, TI-92 Plus, Voyage™ 200 and the TI-Nspire™ Handheld in TI-84 Plus Mode. Implied and explicit multiplication is given the same priority.

>> No.3788071

112/10

successful troll is successful
well done op

>> No.3788190

>not using prefix or postfix notation where parenthesis isn't needed and there's zero ambiguity.
what are you, some kind of retard?

>> No.3788207

>parenthesis isn't
what are you, some kind of retard?

>> No.3788213

>>3788190
>>3787588

>> No.3788235

>>3788207
>what
What are you, some kind of retard?

>> No.3788376

I think this would help.
(* (+ 9 3) (/ 48 2))