Is xy > 0?
1. x - y > -2
2. x - 2y < -6
okay, my understanding is, if its not specified whether x and y are equal to zero, we can consider them or one of them as zero. ( pls dont SC my previous sentence.. its totally crazy i know.. LOLZ!!)
but the answer is
C
can someone share some insight?
Cheers,
Pd
GMAT prep : Is xy > 0?
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- Pdgmat2010
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if xy > 0 both x and y has to have same sign,clearly from either statements we cannot conclude this.
combining
x>y-2 and x<2y-6
so 2y-6>y-2
or y>4..so y is positive
x>4-2 or x>2..hence x is also positive..so xy>0..sufficient
Ans option C
combining
x>y-2 and x<2y-6
so 2y-6>y-2
or y>4..so y is positive
x>4-2 or x>2..hence x is also positive..so xy>0..sufficient
Ans option C
"If you don't know where you are going, any road will get you there."
Lewis Carroll
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LR how did u decide X>4-2???liferocks wrote:if xy > 0 both x and y has to have same sign,clearly from either statements we cannot conclude this.
combining
x>y-2 and x<2y-6
so 2y-6>y-2
or y>4..so y is positive
x>4-2 or x>2..hence x is also positive..so xy>0..sufficient
Ans option C
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- Patrick_GMATFix
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Liferock's explanation is great.
An alternative in merging statements is to do the following:
(1) x-y > -2
(2) x-2y < -6
Multiply (1) by -2 to get -2x+2y < 4. Add this to (2) and you'll end up with -x<-2 --> x>2
Multiply (2) by -1 to get -x+2y > 6. Add this to (1) and you'll end up with y>4
So x>2 and y>4. We have enough data to know that xy>0. The answer is C
A video solution is available at GMATPrep question 1125
Good luck,
-Patrick
An alternative in merging statements is to do the following:
(1) x-y > -2
(2) x-2y < -6
Multiply (1) by -2 to get -2x+2y < 4. Add this to (2) and you'll end up with -x<-2 --> x>2
Multiply (2) by -1 to get -x+2y > 6. Add this to (1) and you'll end up with y>4
So x>2 and y>4. We have enough data to know that xy>0. The answer is C
A video solution is available at GMATPrep question 1125
Good luck,
-Patrick
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