# I really need help!!!

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### #21 kavlas

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Posted 12 May 2011 - 10:38 PM

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

well ,the proof is high school level and it is the following:

=...........................................by using the definition of division:

==..................................................by using the theorem : and the axiom : 1a =a

==...................................................by using the axiom : (ab)c =a(bc)

==..................................................by using the theorem in Natural Nos 48 =24.2

==....................................................by using again the axiom : (ab)c = a(bc)

==............................................................................by using the axiom : and also the axiom :1a = a

=................................................................................by using again the definition of division
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### #22 DJBruce

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Posted 12 May 2011 - 10:57 PM

Umm, you assumed that the OP's ambiguous statement means , and surely there is no argument that if this is the case then it does equal , however, the point is that this statement is ambiguous since we are not sure whether it means or , and that you cannot prove the convention of how we interoperate the OP's expression.

Edited by DJBruce, 12 May 2011 - 11:01 PM.

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### #23 kavlas

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Posted 12 May 2011 - 11:20 PM

48÷2y

=24y or 24/y?

Umm, you assumed that the OP's ambiguous statement means , and surely there is no argument that if this is the case then it does equal , however, the point is that this statement is ambiguous since we are not sure whether it means or , and that you cannot prove the convention of how we interoperate the OP's expression.

Well ,what did the OP asked??

Is there any mathematical book in the whole history of mathematics in which 48÷2y can be equal to ???
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### #24 DJBruce

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Posted 13 May 2011 - 12:33 AM

Well ,what did the OP asked??

Is there any mathematical book in the whole history of mathematics in which 48÷2y can be equal to ???

As the OP indicated by saying, "=24y or 24/y?" the he was asking how we would interoperate the expression given. As for where has 48÷2y been equal to:

,

according the standard oder of operations taught in children operations should be evaluated in the following order Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction (PEMDAS), and when operations of equivalent order are next to each other they are evaluated from left to right. Meaning that since division and multiplication of are same order we would evaluate 48÷2y as being (48÷2)y --since division furthest to the left.

http://www.purplemat...es/orderops.htm
http://www.mathsisfu...der-pemdas.html
http://www.math.com/...s/S2U1L2GL.html

Edited by DJBruce, 13 May 2011 - 12:35 AM.

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### #25 rktpro

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Posted 13 May 2011 - 12:57 AM

2y should be treated as one term because when you get a value for the variable y it is to be multiplied with two. Taking y separately would hamper the result. The co-efficient is always taken with the variable to get exact result.
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### #26 Bignose

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Posted 13 May 2011 - 02:27 AM

Is there any mathematical book in the whole history of mathematics in which 48÷2y can be equal to ???

I've read enough scientific papers, and especially older ones, that I have seen it both ways. It was disconcerting, but in the end, dimensional analysis showed what the author meant. Believe me, I then scratched in my own sets of brackets into the equation to make it clear next time I read it. Back in the day, when it wasn't easy to typeset equations unless they were all in the same line, there were occasionally ambiguous terms printed.
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### #27 Vastor

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Posted 13 May 2011 - 06:30 AM

ermm, i bit confused here...

doesn't that (48/2)y = 48y / 2y

so, how can 48/2y = (48/2)y

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### #28 timo

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Posted 13 May 2011 - 07:10 AM

ermm, i bit confused here...

doesn't that (48/2)y = 48y / 2y

It indeed does not. You've probably mixed that up with the distribution law (48 + 2)y = 48y + 2y.
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### #29 Vastor

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Posted 13 May 2011 - 12:51 PM

It indeed does not. You've probably mixed that up with the distribution law (48 + 2)y = 48y + 2y.

then, what's the distribution law for '/' ?
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### #30 DJBruce

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Posted 13 May 2011 - 07:05 PM

then, what's the distribution law for '/' ?

In this instance there is really only one distributive property, and that is the distribution of multiplication over addition ie: a(b+c)=ab+ac.
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### #31 Cap'n Refsmmat

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Posted 13 May 2011 - 07:59 PM

ermm, i bit confused here...

doesn't that (48/2)y = 48y / 2y

If this were true...

One could divide out the y:

And hence doing (48/2)y would be no different from doing (48/2), and clearly that can't be true.

This is what really happens:

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### #32 kavlas

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Posted 13 May 2011 - 10:28 PM

As the OP indicated by saying, "=24y or 24/y?" the he was asking how we would interoperate the expression given. As for where has 48÷2y been equal to:

,

according the standard oder of operations taught in children operations should be evaluated in the following order Parentheses, Exponents, Multiplication and Division, and Addition and Subtraction (PEMDAS), and when operations of equivalent order are next to each other they are evaluated from left to right. Meaning that since division and multiplication of are same order we would evaluate 48÷2y as being (48÷2)y --since division furthest to the left.

http://www.purplemat...es/orderops.htm
http://www.mathsisfu...der-pemdas.html
http://www.math.com/...s/S2U1L2GL.html

How much is 48÷2 ??

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### #33 Vastor

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Posted 14 May 2011 - 12:19 PM

If this were true...

One could divide out the y:

And hence doing (48/2)y would be no different from doing (48/2), and clearly that can't be true.

This is what really happens:

ahh i see, so from my understanding, (48/2)y not equal to 48/2y doesn't ??

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### #34 Cap'n Refsmmat

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Posted 14 May 2011 - 02:57 PM

48/2y is kind of ambiguous, since it could mean (48/2)y or 48/(2y), depending on what the author means.
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### #35 kavlas

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Posted 16 May 2011 - 03:17 PM

48/2y is kind of ambiguous, since it could mean (48/2)y or 48/(2y), depending on what the author means.

How much is ,48/2 ,

Edited by kavlas, 16 May 2011 - 03:25 PM.

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### #36 rktpro

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Posted 17 May 2011 - 12:38 AM

How much is ,48/2 ,

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### #37 kavlas

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Posted 17 May 2011 - 09:52 AM

The question now is: Does Cap'n Refsmmat agree with you ??
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### #38 imatfaal

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Posted 17 May 2011 - 12:36 PM

The question now is: Does Cap'n Refsmmat agree with you ??

Dollars to donuts he does. Your first question of the thread was ambiguous - your post had two phrases both clear. That's one of the benefits of using latex as soon as you have multiple levels of brackets or division
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### #39 Cap'n Refsmmat

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Posted 17 May 2011 - 02:56 PM

Indeed I do agree.
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### #40 kavlas

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Posted 17 May 2011 - 03:06 PM

Dollars to donuts he does. Your first question of the thread was ambiguous - your post had two phrases both clear. That's one of the benefits of using latex as soon as you have multiple levels of brackets or division

What was my first question of the thread .....?
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