Hello
The question is more of a conceptual one rather than an actual GMAT PS.
Q. If A^2 -B^2 > 0
Answer true or false
Is A>B and A<-B ?
Request you to please elaborate your thought process. Thank you
A^2 -B^2 > 0
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- jainpiyushjain
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(A² - B²) = (A - B)(A + B) > 0jainpiyushjain wrote:Q. If A² -B² > 0
Answer true or false
Is A>B and A<-B ?
Hence, either
- (A - B) > 0 and (A + B) > 0 ---> A > B and A > -B
OR
(A - B) < 0 and (A + B) < 0 ---> A < B and A < -B
Hence, the statement is FALSE (if answering in true/false) or NO (if answering in yes/no).
Last edited by Anju@Gurome on Wed Mar 13, 2013 1:49 am, edited 1 time in total.
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EDIT:
in my original post, i read the inequality signs backward (ah, the joy of being dyslexic).
i've deleted the discussion of things that the problem didn't actually say.
(:
in my original post, i read the inequality signs backward (ah, the joy of being dyslexic).
i've deleted the discussion of things that the problem didn't actually say.
(:
Last edited by lunarpower on Wed Mar 13, 2013 1:34 am, edited 1 time in total.
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--> this actually answers the question, then. i.e., anything of the form "true statement AND false statement" is false. so, you've actually proved that the answer is "no", not "we can't tell".Anju@Gurome wrote:So without any other information it is impossible to answer your question as in either case the answer will be YES for one half and NO for the other half.
the problem here is, of course, the initial confusion created by the strange problem statement.
Last edited by lunarpower on Wed Mar 13, 2013 1:34 am, edited 1 time in total.
Ron has been teaching various standardized tests for 20 years.
--
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Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
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I agree with you but then again he asked to answer in "true or false".lunarpower wrote:--> this actually answers the question, then. i.e., anything of the form "true statement AND false statement" is false. so, you've actually proved that the answer is "no", not "we can't tell".Anju@Gurome wrote:So without any other information it is impossible to answer your question as in either case the answer will be YES for one half and NO for the other half.
It should be other way around, i.e. B < A < -Blunarpower wrote:my first comment here is that you'll never see anything that looks like this:if you have simultaneous inequalities that both involve the same quantity -- here, "A" -- then they should be combined. so, this question should be written as follows:jainpiyushjain wrote:Is A>B and A<-B ?
"Is -b < a < b?"
If you are suggesting a modification of the question or what the question should've been then ignore this part of the post.
Last edited by Anju@Gurome on Wed Mar 13, 2013 1:54 am, edited 1 time in total.
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ah, i read the inequality signs backwards. thanks.Anju@Gurome wrote: I think what he has asked cannot be combined to any simple inequality as both of them together never going to hold true.
If you are suggesting a modification of the question or what the question should've been then ignore this part of the post.
i will edit my post.
on the other hand, my other observation still holds: if you have "statement 1 AND statement 2", and you know that exactly one of statements 1 and 2 is true while the other is false, then "statement 1 AND statement 2" is false. it's not indeterminate -- "yes AND no" = no.
"true AND false" is false.
Ron has been teaching various standardized tests for 20 years.
--
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Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
--
Learn more about ron
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--
Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
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Yes, I agree.lunarpower wrote:on the other hand, my other observation still holds: if you have "statement 1 AND statement 2", and you know that exactly one of statements 1 and 2 is true while the other is false, then "statement 1 AND statement 2" is false. it's not indeterminate -- "yes AND no" = no.
"true AND false" is false.
Let me edit my reply too.
Anju Agarwal
Quant Expert, Gurome
Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
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Backup Methods : General guide on plugging, estimation etc.
Wavy Curve Method : Solving complex inequalities in a matter of seconds.
§ GMAT with Gurome § Admissions with Gurome § Career Advising with Gurome §
- jainpiyushjain
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Thank you experts.Anju@Gurome wrote:Yes, I agree.lunarpower wrote:on the other hand, my other observation still holds: if you have "statement 1 AND statement 2", and you know that exactly one of statements 1 and 2 is true while the other is false, then "statement 1 AND statement 2" is false. it's not indeterminate -- "yes AND no" = no.
"true AND false" is false.
Let me edit my reply too.