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Updated on: 03 Sep 2015, 07:37
Originally posted by satishreddy on 14 Oct 2010, 20:56.
Last edited by ENGRTOMBA2018 on 03 Sep 2015, 07:37, edited 3 times in total.
Last edited by ENGRTOMBA2018 on 03 Sep 2015, 07:37, edited 3 times in total.
Formatted the question.
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
70% (01:26) correct
30%
(01:51)
wrong
based on 1653
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\(R = 1 + 2*x*y + x^2*y^2\), what is the value of \(x*y\)?
(1) R = 0
(2) x > 0
(1) R = 0
(2) x > 0
15 Oct 2010, 03:30
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R = 1 + 2xy + x^2*y^2, what is the value of xy?
(1) R = 0:
(2) x > 0 --> Clearly insufficient.
Answer: A.
(1) R = 0:
- \(1+2xy+x^2*y^2=0\);
\((xy+1)^2=0\);
\(xy=-1\).
Sufficient.
(2) x > 0 --> Clearly insufficient.
Answer: A.
General Discussion
04 Sep 2015, 04:37
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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.
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.
