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# If zy<xy<0, is |x-z|+|x|=|z|

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Manager
Joined: 19 Oct 2008
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26 Mar 2009, 10:53
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I think this was posted before but I can't find it. Can you please explain your answers:

If zy0

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Senior Manager
Joined: 16 Jan 2009
Posts: 339
Concentration: Technology, Marketing
GMAT 1: 700 Q50 V34
GPA: 3
WE: Sales (Telecommunications)
Re: DS GMAT Prep - Inequalities [#permalink]

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26 Mar 2009, 12:48
If zy<xy<0, is |x-z|+|x|=|z|
1) z<x
2) y>0

we will be able to solve |x-z|+|x|=|z| if we get to know the signs of x and Z.
1) z<x , this just rephrases the given information which is not useful. No infrmation is specified regarding y , so we can not deduce the sign of x or z. INSUFFICIENT.

2)y>0
given : zy<xy<0
if y > 0 , x and z must be less than 0
also z<x<0.

now we can answer the inequality . SUFFICIENT.

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Lahoosaher

Manager
Joined: 19 May 2008
Posts: 156
Location: Mumbai
Re: DS GMAT Prep - Inequalities [#permalink]

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26 Mar 2009, 13:44
I agree - Statement 2 is sufficient - so the answer is B.

What is the OA?
Manager
Joined: 19 Oct 2008
Posts: 87
Re: DS GMAT Prep - Inequalities [#permalink]

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26 Mar 2009, 14:13
Sorry guys, OA is D.
Manager
Joined: 28 Jul 2004
Posts: 135
Location: Melbourne
Schools: Yale SOM, Tuck, Ross, IESE, HEC, Johnson, Booth
Re: DS GMAT Prep - Inequalities [#permalink]

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26 Mar 2009, 14:28
Accountant wrote:
I think this was posted before but I can't find it. Can you please explain your answers:

If zy<xy<0, is |x-z|+|x|=|z|

1) z<x
2) y>0

from given condition zy<xy

from (1), z<x --> y is positive --> z and x, both are negative and z < x. So, simplifying the equation:

LHS = |x-z|+|x| = x-z + (-x) = x-z-x = -z
RHS = |z| = -z (since z<0)

which implies, LHS = RHS , hence (1) is sufficient

from (2) , y> 0 --> z <0, x<0. Noe proceed the same way as above, that will give us a solution.

Both (1) and (2) are sufficient separately. Therefore, answer is (D).
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kris

VP
Joined: 28 Dec 2005
Posts: 1482
Re: DS GMAT Prep - Inequalities [#permalink]

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26 Mar 2009, 19:01
krishan wrote:
Accountant wrote:
I think this was posted before but I can't find it. Can you please explain your answers:

If zy<xy<0, is |x-z|+|x|=|z|

1) z<x
2) y>0

from given condition zy<xy

from (1), z<x --> y is positive --> z and x, both are negative and z < x. So, simplifying the equation:

LHS = |x-z|+|x| = x-z + (-x) = x-z-x = -z
RHS = |z| = -z (since z<0)

which implies, LHS = RHS , hence (1) is sufficient

from (2) , y> 0 --> z <0, x<0. Noe proceed the same way as above, that will give us a solution.

Both (1) and (2) are sufficient separately. Therefore, answer is (D).

Agree 100%

You can rewrite the expression in the question as zy-xy<0 --> y(z-x) < 0. This leads to two options; either y<0 and z-x>0 or y>0 and z-x<0

From stat 1, you know z<x , so just quickly picking numbers, you see that the equality in question never holds.

From stat 2, you know z<x, and same approach as above gives the same result
Senior Manager
Joined: 16 Jan 2009
Posts: 339
Concentration: Technology, Marketing
GMAT 1: 700 Q50 V34
GPA: 3
WE: Sales (Telecommunications)
Re: DS GMAT Prep - Inequalities [#permalink]

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27 Mar 2009, 03:18
I get it now.
Thanks pmenon.

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

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Lahoosaher

Re: DS GMAT Prep - Inequalities   [#permalink] 27 Mar 2009, 03:18
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