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If 1=(x+y)/yx, then y =

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guest 2
 Post subject: If 1=(x+y)/yx, then y =
 Post Posted: Mon Sep 08, 2008 9:45 am 
If 1=(x+y)/yx, then y =

(A)x/(x-1)
(B) x/(x+1)
(C) (x-1)/x
(D) (x+1)/x
(E) x

This should be easy enough, but I can't seem to solve for Y...
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cooper2248817
 Post subject: y
 Post Posted: Mon Sep 08, 2008 2:57 pm 
1=(x+y)/yx

yx=x+y

yx-y=x

y(x-1)=x

y=x/(x-1)

A
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cooper2248817
 Post subject: y
 Post Posted: Mon Sep 08, 2008 2:57 pm 
1=(x+y)/yx

yx=x+y

yx-y=x

y(x-1)=x

y=x/(x-1)

A
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guest2
 Post subject:
 Post Posted: Tue Sep 09, 2008 1:01 pm 
thank you.
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RonPurewal
 Post subject:
 Post Posted: Mon Sep 29, 2008 6:23 am 
Offline
ManhattanGMAT Staff


Posts: 6765
lesson / takeaway:
make sure you know how to solve equations like this, in which the desired variable appears in more than one term.

if that happens, follow the exact procedure used in the posts above this one:
* multiply stuff out
* collect the terms containing the term you want on one side of the equation, and collect the terms not containing that term on the other side of the equation
* factor out the desired term from the terms on its side of the equation
* divide to solve

pretty much the same thing every time.
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