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Question ID 1273

by RaginT » Wed Jun 02, 2010 1:35 am
Hi there,

I have looked at GMATfix for the worked solution to this problem. I am still having difficulty with the following step :

Is - y > y ?

rephrased this means, is y > 0

Can anybody show me why this is the case?
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by gmatmachoman » Wed Jun 02, 2010 1:41 am
RaginT wrote:Hi there,

I have looked at GMATfix for the worked solution to this problem. I am still having difficulty with the following step :

Is - y > y ?

rephrased this means, is y > 0

Can anybody show me why this is the case?
- y > y

= -y -y>0

-2y >0

-y>0

multiply (-1) both sides

y <0

So the rephrase will be is y<0

OR

0 >y

which also means is Y<0 ??
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by jube » Wed Jun 02, 2010 2:09 am
If y is positive i.e. y>0, then false
If y < 0, then true

for e.g. y=2, then -y = -2
-2>2 -- false

y=-2, then -y= - (-2)
2>-2 -- true

hope this helps!
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by selango » Wed Jun 02, 2010 2:15 am
Ragin T,

Rephrasing make the equation easy to solve in DS questions.

Rephrasing is nothing but solving the variables on both side of operators,so that it can deduce into easy terms which make the testing scenario easy.

Often it involves cancelling the common variables on both sides or adding/subtracting the variables.

Once u solve more DS ques u ll b able to understand this technique
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by RaginT » Wed Jun 02, 2010 2:26 am
I don't think either of you have got this : the rephrase is definitely correct : is y > 0?

the full problem and solution is here : https://www.gmatfix.com/solution/1273

my thinking is this :

is - y > y ?

becomes 0 > y - (-y) (take the -y from the other side)
therefore 0 > -2y
therefore is 0 < y ? (flip the sign when the -2 goes over to the other side)

However my other approach gives the opposite answer! :

is - y > y ?

becomes - y -y > 0
or -2y > 0
therefore is y < 0 ? (flip the sign as the -2 is taken over to the other side)

Help!
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by selango » Wed Jun 02, 2010 2:29 am
RaginT wrote:I don't think either of you have got this : the rephrase is definitely correct : is y > 0?

the full problem and solution is here : https://www.gmatfix.com/solution/1273

my thinking is this :

is - y > y ?

becomes 0 > y - (-y) (take the -y from the other side)
therefore 0 > -2y-->Here its wrong..it should be 0>2y and y<0


therefore is 0 < y ? (flip the sign when the -2 goes over to the other side)

However my other approach gives the opposite answer! :

is - y > y ?

becomes - y -y > 0
or -2y > 0
therefore is y < 0 ? (flip the sign as the -2 is taken over to the other side)

Help!
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by selango » Wed Jun 02, 2010 2:31 am
is - y > y ?

becomes 0 > y - (-y) (take the -y from the other side)

therefore 0 > 2y(not 0>-2y)

-->y<0

Hope this clarify
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by gmatmachoman » Wed Jun 02, 2010 2:33 am
selango wrote:
RaginT wrote:I don't think either of you have got this : the rephrase is definitely correct : is y > 0?

the full problem and solution is here : https://www.gmatfix.com/solution/1273

my thinking is this :

is - y > y ?

becomes 0 > y - (-y) (take the -y from the other side)
therefore 0 > -2y-->Here its wrong..it should be 0>2y and y<0


therefore is 0 < y ? (flip the sign when the -2 goes over to the other side)

However my other approach gives the opposite answer! :

is - y > y ?

becomes - y -y > 0
or -2y > 0
therefore is y < 0 ? (flip the sign as the -2 is taken over to the other side)

Help!
@Ragin T

CHeck my previous post.that shuld help u!
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by selango » Wed Jun 02, 2010 2:37 am
I checked the solution in GMAT fix.

1) -y>y should be rephrased to y<0

2) -y<y should be rephrased to y>0

But in the solution its got swapped.
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by Patrick_GMATFix » Wed Jun 02, 2010 8:01 am
RaginT wrote:Hi there,

I have looked at GMATfix for the worked solution to this problem. I am still having difficulty with the following step :

Is - y > y ?

rephrased this means, is y > 0

Can anybody show me why this is the case?
is -y>y should be rephrased to y < 0?

just add y to both sides to get is 0 > 2y, then divide both sides by 2 to get is 0 > y?

Thank you for reporting this mistake. If you see anything similar in the future, please hit "Report Error" next to the solution. Sorry about the confusion

What do you think of the Solutions Engine so far?
-Patrick
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by Patrick_GMATFix » Wed Jun 02, 2010 8:14 am
selango wrote:I checked the solution in GMAT fix.

1) -y>y should be rephrased to y<0

2) -y<y should be rephrased to y>0

But in the solution its got swapped.
Thank you selango. Problem has been fixed.
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