Jump to content


Photo
- - - - -

I really need help!!!


  • Please log in to reply
44 replies to this topic

#21 kavlas

kavlas

    Lepton

  • Senior Members
  • 57 posts

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:

\frac{48}{2y} = 48.\frac{1}{2y}=...........................................by using the definition of division: \frac{a}{b}= a\frac{1}{b}

=48(\frac{1}{2}\frac{1}{y})=..................................................by using the theorem :\frac{1}{a}\frac{1}{b}=\frac{1}{ab} and the axiom : 1a =a

=(48.\frac{1}{2})\frac{1}{y}=...................................................by using the axiom : (ab)c =a(bc)


=[(24.2)\frac{1}{2}]\frac{1}{y}=..................................................by using the theorem in Natural Nos 48 =24.2


=[24(2\frac{1}{2})]\frac{1}{y}=....................................................by using again the axiom : (ab)c = a(bc)



=24\frac{1}{y}=............................................................................by using the axiom : a\neq 0\Longrightarrow a\frac{1}{a}=1 and also the axiom :1a = a


=\frac{24}{y}................................................................................by using again the definition of division
  • 0

#22 DJBruce

DJBruce

    Molecule

  • Senior Members
  • 890 posts
  • LocationBrighton, MI

Posted 12 May 2011 - 10:57 PM

Umm, you assumed that the OP's ambiguous statement means \frac{48}{2y}, and surely there is no argument that if this is the case then it does equal \frac{24}{y}, however, the point is that this statement is ambiguous since we are not sure whether it means \frac{48}{2y} or (\frac{48}{2})y, and that you cannot prove the convention of how we interoperate the OP's expression.

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

  • 0

"To give anything less than your best is to sacrifice the Gift."

"A lot of people run a race to see who is fastest. I run to see who has the most guts, who can punish himself into exhausting pace, and then at the end, punish himself even more."

 

Help the children of Meknes, Morocco 


#23 kavlas

kavlas

    Lepton

  • Senior Members
  • 57 posts

Posted 12 May 2011 - 11:20 PM

Want to ask a moronic question, can anyone answer me!!

482y

=24y or 24/y?





Umm, you assumed that the OP's ambiguous statement means \frac{48}{2y}, and surely there is no argument that if this is the case then it does equal \frac{24}{y}, however, the point is that this statement is ambiguous since we are not sure whether it means \frac{48}{2y} or (\frac{48}{2})y, 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 482y can be equal to (\frac{48}{2})y???
  • 0

#24 DJBruce

DJBruce

    Molecule

  • Senior Members
  • 890 posts
  • LocationBrighton, MI

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 (\frac{48}{2})y???


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:

(\frac{48}{2})y,

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.

To read about the standard order of operations see:
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.

  • 0

"To give anything less than your best is to sacrifice the Gift."

"A lot of people run a race to see who is fastest. I run to see who has the most guts, who can punish himself into exhausting pace, and then at the end, punish himself even more."

 

Help the children of Meknes, Morocco 


#25 rktpro

rktpro

    Molecule

  • Senior Members
  • 626 posts

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.
  • 0
Science is fun, math is rum and music is a sticky gum!

To kill the zombies, click the [+] button -->


#26 Bignose

Bignose

    Maths Expert

  • Resident Experts
  • 2,528 posts
  • LocationIowa

Posted 13 May 2011 - 02:27 AM

Is there any mathematical book in the whole history of mathematics in which 482y can be equal to (\frac{48}{2})y???


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.
  • 0

#27 Vastor

Vastor

    Baryon

  • Senior Members
  • 159 posts

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


  • 0

"put cheesy words here"


#28 timo

timo

    Scientist

  • Senior Members
  • 3,385 posts
  • LocationGermany

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.
  • 0

"Ocean madness is no excuse for ocean rudeness" -- H.J. Farnsworth


#29 Vastor

Vastor

    Baryon

  • Senior Members
  • 159 posts

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 '/' ?
  • 0

"put cheesy words here"


#30 DJBruce

DJBruce

    Molecule

  • Senior Members
  • 890 posts
  • LocationBrighton, MI

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.
  • 0

"To give anything less than your best is to sacrifice the Gift."

"A lot of people run a race to see who is fastest. I run to see who has the most guts, who can punish himself into exhausting pace, and then at the end, punish himself even more."

 

Help the children of Meknes, Morocco 


#31 Cap'n Refsmmat

Cap'n Refsmmat

    Mr. Wizard

  • Administrators
  • 11,756 posts
  • LocationTexas

Posted 13 May 2011 - 07:59 PM

ermm, i bit confused here...

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

If this were true...

\frac{48}{2}y = \frac{48y}{2y}

One could divide out the y:

\frac{48y}{2y}=\frac{48}{2}=24

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:

\frac{48}{2}y = \frac{48y}{2}=24y
  • 0

Cap'n Refsmmat
SFN Administrator


#32 kavlas

kavlas

    Lepton

  • Senior Members
  • 57 posts

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 482y been equal to:

(\frac{48}{2})y,

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 482y as being (482)y --since division furthest to the left.

To read about the standard order of operations see:
http://www.purplemat...es/orderops.htm
http://www.mathsisfu...der-pemdas.html
http://www.math.com/...s/S2U1L2GL.html

How much is 482 ??


  • 0

#33 Vastor

Vastor

    Baryon

  • Senior Members
  • 159 posts

Posted 14 May 2011 - 12:19 PM

If this were true...

\frac{48}{2}y = \frac{48y}{2y}

One could divide out the y:

\frac{48y}{2y}=\frac{48}{2}=24

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:

\frac{48}{2}y = \frac{48y}{2}=24y



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


  • 0

"put cheesy words here"


#34 Cap'n Refsmmat

Cap'n Refsmmat

    Mr. Wizard

  • Administrators
  • 11,756 posts
  • LocationTexas

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.
  • 0

Cap'n Refsmmat
SFN Administrator


#35 kavlas

kavlas

    Lepton

  • Senior Members
  • 57 posts

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 ,\frac{48(x-a)^2}{2(x-a)}??

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

  • 0

#36 rktpro

rktpro

    Molecule

  • Senior Members
  • 626 posts

Posted 17 May 2011 - 12:38 AM

How much is ,48/2 ,\frac{48(x-a)^2}{2(x-a)}??


{24(x-a)}
  • 0
Science is fun, math is rum and music is a sticky gum!

To kill the zombies, click the [+] button -->


#37 kavlas

kavlas

    Lepton

  • Senior Members
  • 57 posts

Posted 17 May 2011 - 09:52 AM

{24(x-a)}


The question now is: Does Cap'n Refsmmat agree with you ??
  • 0

#38 imatfaal

imatfaal

    lazy do-nothing mudslinger

  • Moderators
  • 7,223 posts
  • LocationSt James's Park

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
  • 0

A little learning is a dangerous thing; drink deep, or taste not the Pierian spring:
there shallow draughts intoxicate the brain, and drinking largely sobers us again.

- Alexander Pope

 

feel free to click the green arrow  ---->

 


#39 Cap'n Refsmmat

Cap'n Refsmmat

    Mr. Wizard

  • Administrators
  • 11,756 posts
  • LocationTexas

Posted 17 May 2011 - 02:56 PM

Indeed I do agree.
  • 0

Cap'n Refsmmat
SFN Administrator


#40 kavlas

kavlas

    Lepton

  • Senior Members
  • 57 posts

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 .....?
  • 0




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users