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## absolute value !!!!!!!!!!!!!!!

tagged by: Shalabh's Quants

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charmaine Rising GMAT Star
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absolute value !!!!!!!!!!!!!!! Tue Jun 10, 2008 2:04 pm
Elapsed Time: 00:00
• Lap #[LAPCOUNT] ([LAPTIME])
there are an absolute value of the subject, how is it so that kind is xlyl >= lxl y?
a) lxl <= -y
b) lyl <= -x

help plz ! thanksss

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sanju09 GMAT Instructor
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Tue Apr 24, 2012 5:07 am
charmaine wrote:
there are an absolute value of the subject, how is it so that kind is xlyl >= lxl y?
a) lxl <= -y
b) lyl <= -x

help plz ! thanksss
You help us rather; I’m befuddled to see this old post.

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The laws of nature are but the mathematical thoughts of God. ~Euclid

shantanu86 Rising GMAT Star
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Tue Apr 24, 2012 11:18 pm
charmaine wrote:
there are an absolute value of the subject, how is it so that kind is xlyl >= lxl y?
a) lxl <= -y
b) lyl <= -x

help plz ! thanksss
Hi sanju09, charmaine,

x|y| >= |x|y.. (1.)

We know that abs value of a number is always >=0.. therefore (1.) can be true only if y is negative or 0 irrespective of x (x if positive '>' will happen, if negative or 0 '=' will happen.)

a.) alone tells that y is negative..

Hence, [A] is the correct answer.

Hope it helps!!

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spartacus1412 Really wants to Beat The GMAT!
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Wed Apr 25, 2012 9:45 pm
I think both together would be required to comclude that |x|y > = |y|x

from A , we conclude that y <0, no information about x is supplied.--INSUFFICIENT
from B , we conclude that x <0, no information about y is supplied.--INSUFFICIENT

combine them , x<0 and y<0

they hence |x|y and |y|x would be equal to each other.

Hope I was clear.

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shantanu86 Rising GMAT Star
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Wed Apr 25, 2012 10:22 pm
spartacus1412 wrote:
I think both together would be required to comclude that |x|y > = |y|x

from A , we conclude that y <0, no information about x is supplied.--INSUFFICIENT
from B , we conclude that x <0, no information about y is supplied.--INSUFFICIENT

combine them , x<0 and y<0

they hence |x|y and |y|x would be equal to each other.

Hope I was clear.
Hi spartacus1412,

Please read my earlier explanation once again and let me know if you have doubts.

As an illustration, let me use an example to reject your solution and establish mine..

let y = -3, x= +/- 5

My argument is that y= -3 is sufficient. Let's evaluate..

Case x = +5
x|y| = 15, |x|y = -15
hence, x|y| >= |x|y

Case x = -5
x|y| = -15, |x|y = -15
hence, x|y| >= |x|y

From this we can safely conclude that sign of x is not required and only y has to be negative for inequality to hold.

Hope it helps!!

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sanju09 GMAT Instructor
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Thu Apr 26, 2012 3:35 am
shantanu86 wrote:
charmaine wrote:
there are an absolute value of the subject, how is it so that kind is xlyl >= lxl y?
a) lxl <= -y
b) lyl <= -x

help plz ! thanksss
Hi sanju09, charmaine,

x|y| >= |x|y.. (1.)

We know that abs value of a number is always >=0.. therefore (1.) can be true only if y is negative or 0 irrespective of x (x if positive '>' will happen, if negative or 0 '=' will happen.)

a.) alone tells that y is negative..

Hence, [A] is the correct answer.

Hope it helps!!
Oh I see, I thought "there are an absolute value of the subject, how is it so that kind" to be the part of question stem and got confused.

_________________
The laws of nature are but the mathematical thoughts of God. ~Euclid

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