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April 27th, 2013, 09:09 PM   #1
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Algebra simplification

Hi!

I am unsure of the intermediate steps in these equations:

1.



When I multiply through by -1, the equations don't remain equal. What's the intermediate step?



2.

My simplification gives:
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April 28th, 2013, 04:28 AM   #2
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Re: Algebra simplification

1. If you mean , multiply through by 3.

2.
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April 28th, 2013, 04:44 AM   #3
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Quote:
Originally Posted by Aftermath
When I multiply through by -1, the equations don't remain equal.
That doesn't make sense, as the equations (x - 3) = 18 and -(x - 3) = -18 are equivalent. Why would you want to multiply by -1 anyway? This problem started with an expression; should it have started with an equation?
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April 28th, 2013, 02:41 PM   #4
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Re: Algebra simplification

Thank you.

Quote:
Originally Posted by greg1313
1. If you mean , multiply through by 3.




[/quote]2. [/quote]
I just realized that the two (2) is a shared denominator.
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April 28th, 2013, 02:45 PM   #5
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Quote:
Originally Posted by skipjack
Quote:
Originally Posted by Aftermath
When I multiply through by -1, the equations don't remain equal.
That doesn't make sense, as the equations (x - 3) = 18 and -(x - 3) = -18 are equivalent. Why would you want to multiply by -1 anyway? This problem started with an expression; should it have started with an equation?
It doesn't make sense indeed, tired post.

I multiply by -1 to remove the negative before the parentheses:





By the way, why is it that multiplying through by -1 doesn't change the sign inside the parentheses:



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April 28th, 2013, 03:10 PM   #6
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The exponentiation would need to be done first, and then the multiplication by -1 could be done by changing the sign of each term within the parentheses, not just the second term within the parentheses.

-(x - 3) = -(x - 6x + 9) = -x + 6x - 9
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