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48÷2(9+3)=?

View Poll Results: 48÷2(9+3)=?

918 47.39%

288

1,019 52.61%

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04-08-2011 , 02:19 PM

#526

splashpot

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Quote:

Originally Posted by TheAvalanche

It's just a stupid question. You cant just mix notations any old how and expect people to follow it.

You start by using childish ÷ sign that never turns up in an equation/formula then halfway through you start using implied multiplication and brackets.

Either write is as 48÷2x(9+3) giving the 288 or 48/2(9+3) as all maths texts would do giving the answer as 2.

I will accept that there seem to be juxtaposition rules that are not universally agreed upon. I will not accept that ÷ is in any way different than /

Quote

04-08-2011 , 02:19 PM

#527

Imaginary F(r)iend

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Join Date: Jun 2008 Posts: 3,281

Quote:

Originally Posted by TheAvalanche

Either write is as 48÷2x(9+3) giving the 288 or 48/2(9+3) as all maths texts would do giving the answer as 2.

Ok, I think the conclusion is that lol America. All math texts? Seriously? WTF? That's just plain wrong and bs since I have American math books.

This is still not debatable.

Last edited by Imaginary F(r)iend; 04-08-2011 at 02:30 PM.

Quote

04-08-2011 , 02:20 PM

#528

stringbetter

adept

Join Date: Feb 2008 Posts: 841

Quote:

Originally Posted by suzzer99

This post is amazing if not a level. In this context, the bar obviously isn't a fraction, it's a ÷, as in the OP.

Here does this help? a÷b/c = (a*b)÷c. It does not equal a*(b÷c).

Quote:

Originally Posted by Yeti

wrong

Quote

04-08-2011 , 02:21 PM

#529

punkass

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Quote:

Originally Posted by JL514

jesus christ

seriously.

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04-08-2011 , 02:40 PM

#530

TheAvalanche

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Join Date: Apr 2011 Posts: 72

Quote:

Originally Posted by splashpot

I will accept that there seem to be juxtaposition rules that are not universally agreed upon. I will not accept that ÷ is in any way different than /

I entirely agree that / is in no way different than ÷

The thing is you have expectations in the notation.

All higher lever maths books will have the implied multiplication so you have to expect a lot of people seeing 2(9+3) will multiply it it is standard. This would be clear given how the equation was written out using the / sign.

As this notation changes in the middle of this one there is no indication as to which rule should be used.

You would expect to see

48/2(9+3) = 2 as I said earlier or

48/2 x (9+3) = 288

If it was written out in a text book.

This time the x and the spaces indicating that the terms are to be treated separately.

Quote

04-08-2011 , 02:45 PM

#531

TheAvalanche

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Join Date: Apr 2011 Posts: 72

Quote:

Originally Posted by Imaginary F(r)iend

Ok, I think the conclusion is that lol America. All math texts? Seriously? WTF? That's just plain wrong and bs since I have American math books.

This is still not debatable.

lol. What kind of maths books do you have? beginners arithmetic?

Get past middle school and you wont see a ÷ sign anywhere.

Quote

04-08-2011 , 02:46 PM

#532

Snoop Todd

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Join Date: Dec 2007 Posts: 2,187

i got a 95% in first year calc 7 years ago, but havent taken much math since.

i looked at this for a long time and i just keep seeing 2. im not entirely sure why though... i think its because im reading it as 2(12) which, imo, =/ 2*12 (when theres math preceding it)... but im not sure if thats right... just feels like it.

i was really hoping for a definitive answer in this thread and skimming the whole thing yielded very little for me. surprised oot hasn't figured this out and id really like it if you would.

i do not think the poll settles much at all given how tight it is.

Quote

04-08-2011 , 02:50 PM

#533

TJayBird

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Join Date: Nov 2003 Posts: 2,682

This thread makes me feel smart

Spoiler:

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04-08-2011 , 02:51 PM

#534

splashpot

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Quote:

Originally Posted by TheAvalanche

You would expect to see

48/2(9+3) = 2 as I said earlier or

48/2 x (9+3) = 288

What would this equal?

48/2(9+3)5 = ?

How far are you supposed to just assume that everything multiplied implicitly is in the denominator?

Quote

04-08-2011 , 02:54 PM

#535

suzzer99

Save the Cheerleader, Save the World

Join Date: Nov 2005 Posts: 100,711

Ok from my Chiefs forum which is also discussing this: Apparently there is actually some legitimate debate in the mathematics community that multiplication by juxtaposition should be done before regular multiplication and division (IE - xy takes precedence over x*y). That could make the problem ambiguous.

Quote:

http://www.purplemath.com/modules/orderops2.htm

The general consensus among math people is that "multiplication by juxtaposition" (that is, multiplying by just putting things next to each other, rather than using the "×" sign) indicates that the juxtaposed values must be multiplied together before processing other operations. But not all software is programmed this way, and sometimes teachers view things differently. If in doubt, ask!

http://mathforum.org/library/drmath/view/57021.html
Alas, my search for an "authority" on this matter has been nearly
fruitless. The closest thing I have found is the convention used by
the _Mathematical Reviews_ of the American Mathematical Society (AMS),
at

Mathematical Reviews Database - Guide for Reviewers
http://www.ams.org/authors/guide-reviewers.html

that "multiplication indicated by juxtaposition is carried out before
division." Thus, in general, for any variables a, b and c, we would
have a/bc = a/(bc) (assuming, of course, that b and c are nonzero).
Indeed, this convention is consistent with what I have seen in many
mathematical books at various levels; for example, on p. 84 of
Allendoerfer and Oakley, _Principles of Mathematics_, 1969 (my
pre-college math book), we find:

(a / b) x (c / d) = a c / b d

which is generally true only if the right side is interpreted as:

(a c) / (b d)

All I know is I have a degree in physics and I know we never gave multiplication by juxtaposition any special precedence. Also I'd like to see an example that uses a parenthesis, like 2(x+y) and explicitly says that multiplying the 2 with what's in the parenthesis should take precedence over any other multiplication or addition at the same peer level.

Quote

04-08-2011 , 02:56 PM

#536

Imaginary F(r)iend

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Quote:

Originally Posted by TheAvalanche

lol. What kind of maths books do you have? beginners arithmetic?

Get past middle school and you wont see a ÷ sign anywhere.

That sign isn't used anywhere nowadays (except on my numpad it seems) but it equals : or / (DIVIDE).

Look where I referred.

The sentence where you claimed that all math texts would give a 2 as an answer.

I skimmed Mathematics for Economists 1st edition, pretty simple book but I couldn't find anywhere that kind of use of divination.

+1 what Suzzer said as well.

(a / b) x (c / d) = a c / b d , if it's written like that is plain wrong.

if it's written like this

Code:

(a/b) x (c/d)= a*c
               -----
                b*d

it's fine.

Just because you leave one sign off doesn't make magical parenthesis. You can use those rules but it's still wrong.

Last edited by Imaginary F(r)iend; 04-08-2011 at 03:18 PM.

Quote

04-08-2011 , 02:58 PM

#537

TheAvalanche

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Join Date: Apr 2011 Posts: 72

Quote:

Originally Posted by splashpot

What would this equal?

48/2(9+3)5 = ?

How far are you supposed to just assume that everything multiplied implicitly is in the denominator?

as it is under the / and in the demominator you would know to use the usual rule and multiply it out. As i said in my post if you wanted the whole thing multiplied by 5 you would see a space and a multiplication sign:

48/2(9+2) x 5

It is has to be written like that so as not to take forever writing down the fractions proper.

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04-08-2011 , 02:59 PM

#538

jjshabado

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I think someone's intelligence has a higher correlation with how many posts they've made in this thread than if they got the right answer above.

Quote

04-08-2011 , 02:59 PM

#539

suzzer99

Save the Cheerleader, Save the World

Join Date: Nov 2005 Posts: 100,711

Quote:

Originally Posted by suzzer99

This post is amazing if not a level. In this context, the bar obviously isn't a fraction, it's a ÷, as in the OP.

Here does this help? a÷b/c = (a*b)÷c. It does not equal a*(b÷c).

Quote:

Originally Posted by Yeti

wrong

Sorry I edited this and got my signs mixed up. I meant:

a÷b*c = (a÷b)*c. It does not equal a÷(b*c)

Quote

04-08-2011 , 03:01 PM

#540

leo doc

Most interesting man on 2p2

Join Date: Jun 2007 Posts: 12,132

Quote:

Originally Posted by TheAvalanche

Get past middle school and you wont see a ÷ sign anywhere.

And that's part of the point for at least some of us. The use of the symbol more clearly divines the answer; to others, that wouldn't seem so.

Not that it matters one wit; but, I'm still interested in the age grouping of the voters.

Quote

04-08-2011 , 03:03 PM

#541

private joker

Most Definitely

Join Date: Oct 2004 Posts: 25,244

Quote:

Originally Posted by suzzer99

Apparently there is actually some legitimate debate in the mathematics community that multiplication by juxtaposition should be done before regular multiplication and division (IE - xy takes precedence over x*y). That could make the problem ambiguous.

ORLY?!

(haha welcome to what the rest of us have been saying 400 posts ago).

After realizing this, go back and look at how maniacally adamant the 288ers (and the 2ers) are in older posts. It's funny.

Quote

04-08-2011 , 03:04 PM

#542

suzzer99

Save the Cheerleader, Save the World

Join Date: Nov 2005 Posts: 100,711

Yeah I admit, I was wrong, and shocked to see there was actually some debate.

Is that the exact ambiguity you were claiming? Because that's the only one. And I still have my doubts just because someone on the Chiefs forum dug up a link. Like I said it was never a debate in my physics program.

Quote

04-08-2011 , 03:05 PM

#543

TheAvalanche

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Join Date: Apr 2011 Posts: 72

Quote:

Originally Posted by Imaginary F(r)iend

Sorry I didn't mean all maths texts would give the answer as 2.

I meant if the book was using implied multiplication with the bracket they would almost certainly be using /

The problem would never even arise as they would not mix the notation and everybody would be clear as to what is being expected.

Bit tilty and didn't mean to sound like such a dick. Again my apologies

Quote

04-08-2011 , 03:08 PM

#544

Jake Stanton

grinder

Join Date: Apr 2009 Posts: 437

Quote:

Originally Posted by Snoop Todd

your seeing it correctly but (the answer isn't 2 though) once you add the numbers in the brackets the problem is solved from left to right.
not right to left, which is why nearly half the forum has answered wrong.

Last edited by Jake Stanton; 04-08-2011 at 03:21 PM.

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04-08-2011 , 03:11 PM

#545

TheAvalanche

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Join Date: Apr 2011 Posts: 72

Quote:

Originally Posted by Imaginary F(r)iend

Jeez man you made my point. where is the ÷ in those equations which is where I say the confusion is arising.

Quote

04-08-2011 , 03:11 PM

#546

madnak

Cooler than Sammy Hagar

Join Date: Aug 2005 Posts: 19,742

Quote:

Originally Posted by jjshabado

I think someone's intelligence has a higher correlation with how many posts they've made in this thread than if they got the right answer above.

Yeah, how a person votes in this poll clearly doesn't say much about that person's intelligence. That would be true even if there were an established answer (lol obscure order of operations question as a test of intelligence), and it's extra true now that we know there isn't.

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04-08-2011 , 03:36 PM

#547

Eurotrash

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Quote:

Originally Posted by PtMx

+1. It's frustrating to me that so many people are using this to feel better about themselves by saying things like "LOL people suck at math". The notation is deliberately misleading and your ability to parse it bears no relation to your ability to do mathematics.

plus one million. this is like the only reasonable person ITT.

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04-08-2011 , 03:37 PM

#548

jogsxyz

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Quote:

Originally Posted by feedmykids

http://en.wikipedia.org/wiki/Order_of_operations

.

"In any case where there is a possibility that the notation might be misinterpreted, it is advisable to use brackets to clarify which interpretation is intended."

That's hidden in the article.