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M31-48

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M31-48  [#permalink]

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New post 20 Jun 2015, 12:04
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A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

55% (00:52) correct 45% (00:51) wrong based on 71 sessions

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Re M31-48  [#permalink]

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New post 20 Jun 2015, 12:04
Official Solution:


If \(y\) is a nonzero integer, what is the value of \(|y|\)?

(1) \(y^2 = |y|\)

Since \(y^2 = |y|^2\), then we have that \(|y|*|y| = |y|\). \(y\) is nonzero, so we can reduce by it: \(|y| = 1\). Sufficient.

(2) \(|y| = |y|!\)

By testing values we can get that this holds true for \(y = +/-1\) as well as for \(y = +/-2\). Thus, \(|y| = 1\) or 2. Not sufficient.


Answer: A
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Re: M31-48  [#permalink]

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New post 06 May 2016, 15:41
Sorry I don't understand why solution 1 is correct, is there anything I need to review to get these kind of questions right? thank you
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Re: M31-48  [#permalink]

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New post 06 May 2016, 19:35
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Avigano wrote:
Sorry I don't understand why solution 1 is correct, is there anything I need to review to get these kind of questions right? thank you


y^2 = |y|..
which are the numbers which are equal to its squares.. 0, 1 and -1 here as we are taking |-1| here..
but we are told y is non-zero, so y =1 or -1.. in both cases the MOD |y| will be 1..
thus suff
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Re: M31-48  [#permalink]

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New post 07 May 2016, 05:33
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Avigano wrote:
Sorry I don't understand why solution 1 is correct, is there anything I need to review to get these kind of questions right? thank you


Theory on Absolute Values: math-absolute-value-modulus-86462.html
The E-GMAT Question Series on ABSOLUTE VALUE: the-e-gmat-question-series-on-absolute-value-198503.html
Properties of Absolute Values on the GMAT: properties-of-absolute-values-on-the-gmat-191317.html
Absolute Value: Tips and hints: absolute-value-tips-and-hints-175002.html

DS Absolute Values Questions to practice: search.php?search_id=tag&tag_id=37
PS Absolute Values Questions to practice: search.php?search_id=tag&tag_id=58

Hard set on Absolute Values: inequality-and-absolute-value-questions-from-my-collection-86939.html

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Re: M31-48  [#permalink]

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New post 10 Dec 2016, 20:07
can some one please explain |y|! ?
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M31-48  [#permalink]

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New post 10 Dec 2016, 22:16
raul17 wrote:
can some one please explain |y|! ?


For this statement Y can have two values:
Y=1... 1!=1

Or

Y=2... 2!=2x1=2

So although the stem points out that Y is not zero, we are left with two possible values for Y (Y could be 1 or 2),

statment 2) alone is not sufficient,

kind regards.
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Re: M31-48  [#permalink]

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New post 13 Jul 2017, 16:34
I was looking at the value of y, not |y|. :oops:
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Re: M31-48   [#permalink] 13 Jul 2017, 16:34
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