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#1 2013-02-03 04:16:57
- Al-Allo
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Proportion
I just have a little problem :
X 8
_= _
7 9
If I would want to solve for X, I would multiply by 7 for each side. Leaving x=56
___
9
But what I did is x=56
__
63
Could somebody explain me why it's wrong ?
Thanks
#2 2013-02-03 05:26:06
- bobbym
- Administrator
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Re: Proportion
When you multiply by 7 you cancel the 7 on the left but not the 9 on bottom right.
Correct thing to do is to cross multiply
9x = 56
x = 56 / 9
In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.
#3 2013-02-03 05:30:18
- Al-Allo
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Re: Proportion
But I mean not canceling the 9 but multiplying it by 7, it's not a right thing to do ? Thanks
#4 2013-02-03 05:34:45
- bobbym
- Administrator
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Re: Proportion
If you multiply by 7 you are going to get:
x = 56 / 9 which is the same thing.
In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.
#5 2013-02-03 06:28:41
- Al-Allo
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Re: Proportion
bobbym wrote:
If you multiply by 7 you are going to get:
x = 56 / 9 which is the same thing.
ok, I understood. Thanks
Last edited by Al-Allo (2013-02-03 06:30:14)
#6 2013-02-03 06:32:09
- bobbym
- Administrator
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Re: Proportion
Hi;
You are welcome.
In mathematics, you don't understand things. You just get used to them.
90% of mathematicians do not understand 90% of currently published mathematics.
I am willing to wager that over 75% of the new words that appeared were nothing more than spelling errors that caught on.