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R = 1 + 2xy + x^2y^2, what is the value of xy?

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R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 14 Oct 2010, 19:56
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65% (01:51) correct 35% (01:14) wrong based on 179 sessions
\(R = 1 + 2*x*y + x^2*y^2\), what is the value of \(x*y\)?

(1) R = 0
(2) x > 0
[Reveal] Spoiler: OA

Last edited by Engr2012 on 03 Sep 2015, 06:37, edited 3 times in total.
Formatted the question.
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Re: R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 15 Oct 2010, 01:20
satishreddy wrote:
R=1+2xy+x^y^, what is the value of xy

1) R=0
2) x>0

OA : A


I think the question you posted is incomplete.

what does y^ mean?? There will be some digit aftger y^.
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Re: R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 15 Oct 2010, 02:30
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satishreddy wrote:
R=1+2xy+x^2*y^2, what is the value of xy

1) R=0
2) x>0

OA : A


Question should be:


R=1+2xy+x^2*y^2, what is the value of xy?

(1) R=0 --> \(1+2xy+x^2*y^2=0\) --> \((xy+1)^2=0\) --> \(xy=-1\). Sufficient.
(2) x>0 --> Clearly insufficient.

Answer: A.


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Re: R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 17 Oct 2010, 23:39
Certainly a tricky one. Thanks for posting
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Re: R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 05 Mar 2015, 00:09
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 03 Sep 2015, 06:29
x^2y^2

I thought x^((2y)^2) :| so I answered E

I think it should be written specifically: x^2*y^2
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Re: R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 03 Sep 2015, 06:38
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trung0808 wrote:
x^2y^2

I thought x^((2y)^2) :| so I answered E

I think it should be written specifically: x^2*y^2


Thank you for raising this issue. I have formatted the question.
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R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 04 Sep 2015, 03:37
Expert's post
Forget conventional ways of solving math questions. In DS, Variable approach is

the easiest and quickest way to find the answer without actually solving the

problem. Remember equal number of variables and equations ensures a solution.



R=1+2xy+(xy)^2, what is the value of x∗y ?

(1) R = 0
(2) x > 0

==> transforming the original condition and the question by variable approach method, we have, R=(1+xy)^2, 1+xy=R, -R, then xy=R-1, xy=-R-1. if we know R we can find xy
In case of 1), if R=0 then xy=-1, a unique answer. Therefore it is sufficient. Thus A is the answer.
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Re: R = 1 + 2xy + x^2y^2, what is the value of xy? [#permalink] New post 04 Sep 2015, 03:58
MathRevolution wrote:
Forget conventional ways of solving math questions. In DS, Variable approach is

the easiest and quickest way to find the answer without actually solving the

problem. Remember equal number of variables and equations ensures a solution.



R=1+2xy+(xy)^2, what is the value of x∗y ?

(1) R = 0
(2) x > 0

==> transforming the original condition and the question by variable approach method, we have, R=(1+xy)^2, 1+xy=R, -R, then xy=R-1, xy=-R-1. if we know R we can find xy
In case of 1), if R=0 then xy=-1, a unique answer. Therefore it is sufficient. Thus A is the answer.



If you know our own innovative logics to find the answer, you don’t need to

actually solve the problem.
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Your actual solution is very difficult to find in the quoted post and your advertisement. Can you please reduce the size of your advertisement text? or better put it in your signatures. This way your posts will be useful for people in this forum.

Also, put the quoted post in proper formatting, so that your actual post is clearly visible.

Thanks
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Re: R = 1 + 2xy + x^2y^2, what is the value of xy?   [#permalink] 04 Sep 2015, 03:58
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