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Gmat Prep

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Source: — Data Sufficiency |

Re: Gmat Prep

by maihuna » Mon Oct 26, 2009 9:48 am
John Corn wrote:x not equal to -y

is (x-y)/(x+y)>1?

1) x>0
2) y<0

Please help [/u]
x-y
---- -1 > 0
x+y

x-y-x-y
-------- >0
x+y

y/(x+y) < 0

If x>0 we do not know anything about y insuff
If y<0 we do not know anything abt x insuff

If x>0 and y<0 depends on its value for the sign of x+y, not since y<0 the sum y/(x+y) < 0 means 1/(x+y) > 0 but that is not always true, if y=-2 x =1 we have x+y = -1 while y=-2 x=3 means x+y =1

so E.
Charged up again to beat the beast :)
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by John Corn » Mon Oct 26, 2009 10:30 am
Thanks maihuna for your response.
I have a question

Why can't you solve it with this equality
(x-y)>(x+y)?

With this I am getting that B is sufficient.

Thanks in advance.
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by xcusemeplz2009 » Mon Oct 26, 2009 12:18 pm
John Corn wrote:Thanks maihuna for your response.
I have a question

Why can't you solve it with this equality
(x-y)>(x+y)?

With this I am getting that B is sufficient.

Thanks in advance.
in inequalities dividing or multipying any unknown variable(+or-ve) always leads to two outcomes a positive or a negative

since x-y is + or -ve it is unknown cross multiplying may or may not req change of sign....

therefore whn sign is unknown its always better to limit the operation upto addition or sub...

HTH
It does not matter how many times you get knocked down , but how many times you get up
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by John Corn » Mon Oct 26, 2009 1:39 pm
Thanks so much.
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Re: Gmat Prep

by life is a test » Wed Oct 28, 2009 8:12 am
maihuna wrote: x-y-x-y
-------- >0
x+y

y/(x+y) < 0
maihuna - is the second formula supposed to read 2y/x+y?

I dont think it makes a difference to the ans but just wanted to check i was reducing it correctly when i worked it out.

thks
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Quick Question

by chris6 » Fri Oct 30, 2009 9:21 am
x-y
---- -1 > 0
x+y

How did you get -x-y in the numerator from -1?

x-y-x-y
-------- >0
x+y
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i have a question!

by khushboo143 » Sun Nov 01, 2009 3:25 pm
x-y
---- -1 > 0
x+y

x-y-x-y
-------- >0
x+y

till here i got it but then hoe did u got the below step..

y/(x+y) < 0

i got stucked at
-2y
---- > 0
x+y

pls help!!!
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