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# If xy > 0, does xy y = 3? (1) xy = 3 (2) y 1 = 0

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Director
Joined: 07 Jun 2004
Posts: 599
Location: PA
If xy > 0, does xy y = 3? (1) xy = 3 (2) y 1 = 0  [#permalink]

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04 Dec 2010, 02:10
1
3
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Difficulty:

75% (hard)

Question Stats:

54% (01:51) correct 46% (01:52) wrong based on 297 sessions

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If xy > 0, does xy – y = 3?

(1) xy = 3
(2) y – 1 = 0

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Math Expert
Joined: 02 Sep 2009
Posts: 51291

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04 Dec 2010, 02:22
3
1
rxs0005 wrote:
If xy > 0, does xy – y = 3?

(1) xy = 3
(2) y – 1 = 0

If xy > 0, does xy – y = 3?

(1) xy = 3 --> question becomes: is $$3-y=3$$? or is $$y=0$$? Since given that $$xy>0$$ (or the same $$xy=3$$) then it's clear that $$y\neq{0}$$ so we have the answer NO. Sufficient.

(2) y – 1 = 0 --> question becomes: is $$x=4$$? We don't know that. Not sufficient.

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04 Dec 2010, 03:21
1
thanks great explanation
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Manager
Joined: 02 Oct 2010
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19 Dec 2010, 21:22
Bunuel wrote:
rxs0005 wrote:
If xy > 0, does xy – y = 3?

(1) xy = 3
(2) y – 1 = 0

If xy > 0, does xy – y = 3?

(1) xy = 3 --> question becomes: is $$3-y=3$$? or is $$y=0$$? Since given that $$xy>0$$ (or the same $$xy=3$$) then it's clear that $$y\neq{0}$$ so we have the answer NO. Sufficient.
(2) y – 1 = 0 --> question becomes: is $$x=4$$? We don't know that. Not sufficient.

Good Explanation....
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24 Jan 2011, 00:47
Bunuel wrote:
rxs0005 wrote:
If xy > 0, does xy – y = 3?

(1) xy = 3
(2) y – 1 = 0

If xy > 0, does xy – y = 3?

(1) xy = 3 --> question becomes: is $$3-y=3$$? or is $$y=0$$? Since given that $$xy>0$$ (or the same $$xy=3$$) then it's clear that $$y\neq{0}$$ so we have the answer NO. Sufficient.
(2) y – 1 = 0 --> question becomes: is $$x=4$$? We don't know that. Not sufficient.

Great! With your explanations, I am getting better at seeing through the equations and manipulating them! Thanks Kudos!
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Re: If xy > 0, does xy y = 3? (1) xy = 3 (2) y 1 = 0  [#permalink]

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03 Jul 2013, 00:17
Bumping for review and further discussion*. Get a kudos point for an alternative solution!

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Re: If xy > 0, does xy y = 3? (1) xy = 3 (2) y 1 = 0  [#permalink]

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03 Jul 2013, 03:01
1
From (1), xy-y = 3-y ; this is equal to 3 only if y=0 , but since its given that xy =3 neither x nor y can be 0. Therefore, given (1) xy-y is not equal to 3. Sufficient.
(2) simplifies the question to is x-1=3 or is x=4 which cannot be answered with this information. Insufficient.
Director
Joined: 25 Apr 2012
Posts: 683
Location: India
GPA: 3.21
Re: If xy > 0, does xy y = 3? (1) xy = 3 (2) y 1 = 0  [#permalink]

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03 Jul 2013, 08:29
1
rxs0005 wrote:
If xy > 0, does xy – y = 3?

(1) xy = 3
(2) y – 1 = 0

From the given statement xy>0, we can deduce that either x,y>0 or x,y< 0

St1 we have xy=3
possible values of x and y are

x=-1, y=-3, substituting in the given we get 3-(-3)=6 which is not equal to 3
x=3,y=1, we get 3-1= 2 not equal 3
x=9,y=1/3 3- 1/3= 8/3 not equal to 3

we can safely that say that for any values satisfying given st1 we do not have the expression value equal 3

Hence Option B,C,E ruled out

St 2, y-1=0-----> y=1
we know only the value of y and that x>0 which is not sufficient. In order to satisfy the given equation that is xy-y=3 value of x should be 4 which we are not sure of.

Hence Ans should be A

thanks
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Re: If xy > 0, does xy y = 3? (1) xy = 3 (2) y 1 = 0  [#permalink]

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17 Aug 2018, 16:52
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: If xy > 0, does xy y = 3? (1) xy = 3 (2) y 1 = 0 &nbs [#permalink] 17 Aug 2018, 16:52
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