# I really need help!!!

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### #1 RealFunnyFungi

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Posted 26 April 2011 - 11:53 AM

48÷2y

=24y or 24/y?
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### #2 Spyman

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Posted 26 April 2011 - 12:12 PM

Place the equation this way and it will be easier to see:

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### #3 RealFunnyFungi

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Posted 26 April 2011 - 12:20 PM

So that means i need to treat 2y as 1 term?
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### #4 timo

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Posted 26 April 2011 - 12:29 PM

I'm afraid no one can answer that for you, except the person who gave you the ambiguous term. I would interpret it the way Spyman did (as ), but that's just from my taste of aesthetics, not because I'd know some rule that this surely cannot mean .

Edited by timo, 26 April 2011 - 12:33 PM.

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### #5 Spyman

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Posted 26 April 2011 - 12:32 PM

So that means i need to treat 2y as 1 term?

Otherwise it should have been:

(48/2)y = 24y
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### #6 timo

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Posted 26 April 2011 - 12:34 PM

Do you know that or do you just assume that because it is intuitive, Spyman?

Edited by timo, 26 April 2011 - 12:34 PM.

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### #7 RealFunnyFungi

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Posted 26 April 2011 - 12:35 PM

Well...Thx for ur help

I've also got a question which i guess almost everyone knows lol

is that

48÷2(9+3) = ?
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### #8 Spyman

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Posted 26 April 2011 - 12:46 PM

Do you know that or do you just assume that because it is intuitive, Spyman?

Assume, I am no math expert and don't know any rule for this either.

I guess for this cind of question the math is of such level that multiplication of 2 and y should have precedence.

48÷2(9+3) = ?

Well, I don't think the answer is 24×12, do you?

[EDIT]
Actually I think the general rules are to first perform any calculations inside parentheses and then multiplications/divisions take precedence before additions/subractions and priority is from left to right.

However 48/2(9+3) is different than 48/2×(9+3) since the multiplication sign is significantly missing in the first equation. When it is removed I always intuitive put an extra parentheses around that part making it 48/(2×(9+3)) or 48/(2×y).

Edited by Spyman, 26 April 2011 - 01:06 PM.

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### #9 RealFunnyFungi

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Posted 26 April 2011 - 01:37 PM

well I guess it should be 2 at first but later i asked my classmates and they had different answers

Some are 2 and some are 288

That's why i am confused
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### #10 Xittenn

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Posted 26 April 2011 - 02:14 PM

I usually take 2(9+3) to mean (2(9+3)) and not 2 * (9+3) so I think that 48÷2(9+3) is asking for 48÷(2(9+3)) and the answer is 2. This is also the more logical answer given the context and the numbers.

I think in general, oversights like this are avoided at all costs in literature and they generally constitute a mistake. It is usually pretty clear the intention and this isn't something you should dwell on; there are better uses for your time.

lol
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### #11 ewmon

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Posted 26 April 2011 - 02:22 PM

So that means i need to treat 2y as 1 term?

Just ask yourself: Why would you divide 48 by the 2 but not by the y?

If you had $48 billion, and you had to divide it among 2 hundred people, or 2 thousand people, or 2 million people, you would divide the$48 billion by the 2 *and* the hundred, or thousand, or million.

Edited by ewmon, 26 April 2011 - 02:24 PM.

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### #12 RealFunnyFungi

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Posted 27 April 2011 - 05:59 AM

I usually take 2(9+3) to mean (2(9+3)) and not 2 * (9+3) so I think that 48÷2(9+3) is asking for 48÷(2(9+3)) and the answer is 2. This is also the more logical answer given the context and the numbers.

I think in general, oversights like this are avoided at all costs in literature and they generally constitute a mistake. It is usually pretty clear the intention and this isn't something you should dwell on; there are better uses for your time.

How can you prove that 2(9+3) = (2(9+3))?
I mean the bracket( 2(9+3) ) is added yourself. My primary teacher told me that brackets are at the first priority to solve and there is no rule of precedence of multiplication and division. That means after solving the brackets, we have
48 ÷ 2(9+3)
=48 ÷ 2 x 12
=288
and that's also quite reasonable , i guess.
Well but my first answer is 2. Truely , i thought it is 2 but the ''288 guys'' still have their own reasons which can't be neglected.
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### #13 Xittenn

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Posted 27 April 2011 - 01:54 PM

It's not an issue of proof, this is not conventional mathematics and this is why this is ambiguous. It's an accepted way of doing things just as 2x really means 2 * x, it is an ugly thing to do but it happens. It is what is called 'implied' . . . . . . . . . . . . .

If you wish to maintain conventional mathematics than indeed the answer is 288, but I can guarantee you 100% that this was not the intention. There are a number of other ways that this could have been written that are, statistically speaking, far more likely to have been used. Given the statistics if you answer 288, well you would be someone who ignores their own better judgment; I mean you are questioning this!

Edited by Xittenn, 27 April 2011 - 02:00 PM.

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### #14 CaptainPanic

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Posted 27 April 2011 - 02:18 PM

So that means i need to treat 2y as 1 term?

Yes.

Just like you can treat "2 eggs" as one term, or "two bananas", "two dollars", or "two hours". You don't just have "two". You have to specify "two what?".
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### #15 Spyman

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Posted 27 April 2011 - 03:56 PM

well I guess it should be 2 at first but later i asked my classmates and they had different answers

Some are 2 and some are 288

That's why i am confused

Was not this a test you have finished and as of which you now could ask your teacher for the intention and answer of the question?

Or are you trolling and trying to stirr up fuzz?
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### #16 DrRocket

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Posted 28 April 2011 - 02:37 AM

well I guess it should be 2 at first but later i asked my classmates and they had different answers

Some are 2 and some are 288

That's why i am confused

The general rule in mathematics is to be clear.

"48÷2(9+3)" is not clear. To make it clear one needs to use parentheses. So one would write either 48÷(2(9+3) or (48÷2)(9+3).

There is no point in arguing over what 48÷2(9+3) is "supposed to mean" as that reqiuires divining the intent of the writer.

The fundamental problem is the symbol "÷" which is not normally used in scientific circles, or polite company, anyway. I have not seen it in regular use since about the third grade (caculators using algebraic notation (ugh!) excepted).

I have been a professional mathematician for over three decades. I understand arithmetic pretty well, but I flunk tests of clairvoyance with regularity. When in doubt ask the author.

Edited by DrRocket, 28 April 2011 - 02:58 AM.

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### #17 kavlas

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Posted 11 May 2011 - 12:01 AM

48÷2y

=24y or 24/y?

nouseforaname do you know that you can actually prove that 48÷2y= 24/y and not 24y??
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### #18 Bignose

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Posted 11 May 2011 - 12:32 AM

nouseforaname do you know that you can actually prove that 48÷2y= 24/y and not 24y??

no, you can't. you can't "prove" (no matter how big a font you use) a convention. You decide on a convention, and stick to it. The question as asked depends on what convention one uses.
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### #19 kavlas

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Posted 11 May 2011 - 12:51 AM

no, you can't. you can't "prove" (no matter how big a font you use) a convention. You decide on a convention, and stick to it. The question as asked depends on what convention one uses.

Well .

Do we not define division in rational and in real Nos a÷b = ??
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### #20 Bignose

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Posted 11 May 2011 - 02:52 AM

Well .

Do we not define division in rational and in real Nos a÷b = ??

How does this "prove" whether the y in the OP's question is in the numerator or denominator?
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