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June 1st, 2014, 08:35 AM   #1
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basic rearrange

Apparently 2y+4=x-3 can be rearranged to x-2y-7=0

If you deduct 2y from both sides of 2y+4=x-3 you get 4=x-3-2y, but I thought if you added 4 the -3 on the right would change to +1. Evidently the operator is disregarded and 4 is added to the 3 on the right.

Sure this is pretty basic, but it's been a long time since I studied this.

cheers
Mark

Last edited by skipjack; June 1st, 2014 at 11:02 AM.
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June 1st, 2014, 10:42 AM   #2
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Hi markcr,

You need to deduct 4 from each side, not add:

$\displaystyle \large
\begin{align}
2y +4 &= x-3 \\
2y+4-2y &= x-3-2y \\
\\
4 &= x-3-2y \\
4-4 &= x-3-2y-4 \\
\\
0 &= x-2y-7 \\
\end{align}
$
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June 1st, 2014, 01:07 PM   #3
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thanks!

I have a feeling this forum is going to be a great help with my endeavours...

Mark
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June 1st, 2014, 01:55 PM   #4
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Quote:
I have a feeling this forum is going to be a great help with my endeavours...
I hope so too. Usually I notice when a new member makes their first post and I say "welcome to the forums".

For some reason, I failed to do so this time, so:

welcome to the forums!
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