Author 
Message 
TAGS:

Hide Tags

Director
Joined: 01 Apr 2008
Posts: 837
Name: Ronak Amin
Schools: IIM Lucknow (IPMX)  Class of 2014

If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
12 Nov 2009, 09:45
14
This post received KUDOS
36
This post was BOOKMARKED
Question Stats:
20% (01:10) correct 80% (01:21) wrong based on 900 sessions
HideShow timer Statistics
If xy ≠ 0, is x > y? (1) 4x = 3y (2) y  x = x  y
Official Answer and Stats are available only to registered users. Register/ Login.



Math Expert
Joined: 02 Sep 2009
Posts: 44592

If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
12 Nov 2009, 10:14
19
This post received KUDOS
Expert's post
18
This post was BOOKMARKED
Economist wrote: If xy ≠ 0, is x > y?
(1) 4x = 3y
(2) y  x = x  y This is a good one. +1 Economist for it. If xy ≠ 0, is x > y?Question asks whether \(x>y\)? (1) 4x = 3y > \(x=\frac{3}{4}y\), well this one is relatively easy. This statement only tells that x and y have the same sign. When they are both positive then \(x<y\), BUT when they are both negative \(y<x\). Not sufficient. (2) \(y  x = x  y\) > \(y  x = (yx)\). This means that \(y  x\leq{0}\) > \(x\geq{y}\). Thus, this statement says that x can be more than or equal to y. Not sufficient. (1)+(2) From (1) (\(x=\frac{3}{4}y\)) it follows that \(x\) is not equal to \(y\) (bearing in mind that xy ≠ 0), hence from (2): \(x>y\). Sufficient. Answer: C.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Director
Joined: 01 Apr 2008
Posts: 837
Name: Ronak Amin
Schools: IIM Lucknow (IPMX)  Class of 2014

1
This post received KUDOS
This is a good question, simple with a small trap



VP
Joined: 05 Mar 2008
Posts: 1428

If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
12 Nov 2009, 10:26
y  x = x  y
y  x = x  y 2x = 2y x=y so answer is no
y + x = xy 0=0 answer is no
sufficient



Math Expert
Joined: 02 Sep 2009
Posts: 44592

1
This post received KUDOS
Expert's post
3
This post was BOOKMARKED
lagomez wrote: 2. y  x = x  y
y  x = x  y 2x = 2y x=y so answer is no
y + x = xy 0=0 answer is no
sufficient
One more thing: the red part is not correct. \(y  x = x  y\). Look at the LHS it's absolute value, it's never negative, hence RHS or \(xy\) is never negative, \(xy>=0\) or \(yx<=0\). If so then only one possibility for \(y  x\), it must be \(y+x\). So we'll have: Condition: \(yx<=0\), which is the same as \(x>=y\) And: \(y  x = x  y\)> \(y+x=xy\), > \(0=0\). The above means that \(y  x = x  y\) is always true for \(x>=y\). But as we concluded earlier it's not enough. We need to be sure that \(x>y\). And \(x>=y\) leaves the possibility that they are equal, which is removed with the statement (1) when considering together. Hence C.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Manager
Joined: 26 May 2005
Posts: 196

Re: Inequalities [#permalink]
Show Tags
Updated on: 11 Feb 2010, 10:06
st 1) y=1, x=3/4  false y=1, x=3/4  true Not sufficient st 2) yx =xy> x>y Sufficient coz x = (x) = x  basically a negative numbers should be negated again to get the result for absolute value all the cases as cay that x>y but fails when x=y combining we can answer the question C <didnt consider x=y option, so answered as B >
Originally posted by chix475ntu on 10 Feb 2010, 22:16.
Last edited by chix475ntu on 11 Feb 2010, 10:06, edited 1 time in total.



CEO
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2673
Location: Malaysia
Concentration: Technology, Entrepreneurship
GMAT 1: 670 Q49 V31 GMAT 2: 710 Q50 V35

Re: Inequalities [#permalink]
Show Tags
11 Feb 2010, 00:08
chix475ntu wrote: st 1) y=1, x=3/4  false y=1, x=3/4  true Not sufficient st 2) yx =xy> x>y Sufficient coz x = (x) = x  basically a negative numbers should be negated again to get the result for absolute value
B B alone is not sufficient as we dont know whether x=y? So A gives information that x is not = y. So Final ans is C This was nice question...even I would have done the same mistake in the exam..Its really important to think of all the possibilities on the G day.
_________________
Fight for your dreams :For all those who fear from Verbal lets give it a fight
Money Saved is the Money Earned
Jo Bole So Nihaal , Sat Shri Akaal
Support GMAT Club by putting a GMAT Club badge on your blog/Facebook
GMAT Club Premium Membership  big benefits and savings
Gmat test review : http://gmatclub.com/forum/670to710alongjourneywithoutdestinationstillhappy141642.html



Math Expert
Joined: 02 Sep 2009
Posts: 44592

Re: Inequalities [#permalink]
Show Tags
11 Feb 2010, 11:55
Given: \(xy\neq0\). Question: is \(x>y\) true? (1) \(4x = 3y\) > if \(x\) and \(y\) are both positive, then \(x<y\) BUT if they are both negative then \(x>y\). Not sufficient. But from this statement we can grasp an important property we'll use while evaluating statements together: as \(xy\neq0\) then from statement (1) \(x\neq{y}\). (2) \(yx=xy\). Now as LHS is absolute value, which is never negative, RHS must also be \(\geq0\) > so \(xy\geq0\) > then \(yx=(yx)\), and we'll get \((yx)=xy\) > \(0=0\), which is true. This means that equation \(yx=xy\) holds true when \(xy\geq0\) or, which is the same, when \(x\geq{y}\). But this not enough as \(x=y\) is still possible. Not sufficient. (1)+(2) From (1) we got that \(x\neq{y}\) and from (2) \(x\geq{y}\), hence \(x>y\). Sufficient. Answer: C. Hope it helps.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 30 Sep 2013
Posts: 1

Re: Inequalities [#permalink]
Show Tags
30 Sep 2013, 14:42
Bunuel wrote: Given: \(xy\neq0\). Question: is \(x>y\) true?
(1) \(4x = 3y\) > if \(x\) and \(y\) are both positive, then \(x<y\) BUT if they are both negative then \(x>y\). Not sufficient. But from this statement we can grasp an important property we'll use while evaluating statements together: as \(xy\neq0\) then from statement (1) \(x\neq{y}\).
(2) \(yx=xy\). Now as LHS is absolute value, which is never negative, RHS must also be \(\geq0\) > so \(xy\geq0\) > then \(yx=(yx)\), and we'll get \((yx)=xy\) > \(0=0\), which is true. This means that equation \(yx=xy\) holds true when \(xy\geq0\) or, which is the same, when \(x\geq{y}\). But this not enough as \(x=y\) is still possible. Not sufficient.
(1)+(2) From (1) we got that \(x\neq{y}\) and from (2) \(x\geq{y}\), hence \(x>y\). Sufficient.
Answer: C.
Hope it helps. Dear Bunuel: I am a bit confused with this problem. I don't have a problem to understand the first statement, but I do have a problem trying to understand the second one.. I saw a user on this thread was solving the second statement as this: 2. y  x = x  y y  x = x  y 2x = 2y x=y y + x = xy 0=0 Isn't his way of solving the correct way to solve this kind of problems? I have seen some other exercises and they always negate the LHS that has the absolute value on it regarding of the inequality symbol or equality. I would like to learn why we are not doing this on this problem. If I am wrong, would you be so kind to revamp the way of solving statement 2, I already read the way you solved it, but it was not 100% clear for me. Thanks in advance.



Math Expert
Joined: 02 Sep 2009
Posts: 44592

Re: Inequalities [#permalink]
Show Tags
01 Oct 2013, 00:34
Aidhen wrote: Bunuel wrote: Given: \(xy\neq0\). Question: is \(x>y\) true?
(1) \(4x = 3y\) > if \(x\) and \(y\) are both positive, then \(x<y\) BUT if they are both negative then \(x>y\). Not sufficient. But from this statement we can grasp an important property we'll use while evaluating statements together: as \(xy\neq0\) then from statement (1) \(x\neq{y}\).
(2) \(yx=xy\). Now as LHS is absolute value, which is never negative, RHS must also be \(\geq0\) > so \(xy\geq0\) > then \(yx=(yx)\), and we'll get \((yx)=xy\) > \(0=0\), which is true. This means that equation \(yx=xy\) holds true when \(xy\geq0\) or, which is the same, when \(x\geq{y}\). But this not enough as \(x=y\) is still possible. Not sufficient.
(1)+(2) From (1) we got that \(x\neq{y}\) and from (2) \(x\geq{y}\), hence \(x>y\). Sufficient.
Answer: C.
Hope it helps. Dear Bunuel: I am a bit confused with this problem. I don't have a problem to understand the first statement, but I do have a problem trying to understand the second one.. I saw a user on this thread was solving the second statement as this: 2. y  x = x  y y  x = x  y 2x = 2y x=y y + x = xy 0=0 Isn't his way of solving the correct way to solve this kind of problems? I have seen some other exercises and they always negate the LHS that has the absolute value on it regarding of the inequality symbol or equality. I would like to learn why we are not doing this on this problem. If I am wrong, would you be so kind to revamp the way of solving statement 2, I already read the way you solved it, but it was not 100% clear for me. Thanks in advance. There can be many correct ways to solve a questions. Try this one: (2) says that \(yx=(yx)\). We know that \(x=x\), when \(x\leq{0}\), thus \(yx\leq{0}\).
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Intern
Joined: 28 Sep 2014
Posts: 18
D: M
WE: Information Technology (Consulting)

Re: If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
20 Oct 2014, 22:26
1
This post received KUDOS
If xy ≠ 0, is x > y?
(1) 4x = 3y
(2) y  x = x  y
Consider (1) 4x=3y ; x=3/3 and y =4/4 satisfy this condition. so x can be > y or x can be <y. insufficient
Consider (2)
y  x = x  y x= 4 y =3 satisfy this , and x>y x= 3 y=3 satisfy this but x =y x= 3 and y = 4 doesnt satisfy x=3 and y =4 satisfy this and x >y hence insufficient
combining 1 and 2 the only option that satisfy 1 and 2 is x=3 and y=4 and hence x>y
Therefore C is the answer.



Current Student
Joined: 04 Jul 2015
Posts: 7
Location: India
Concentration: Technology, Strategy
Schools: CBS '19, Tuck '19, Duke '19, Anderson '19, Johnson '19, KenanFlagler '19, Marshall '19, HEC Sept'16, HEC Jan'16, ISB '18 (A), Smeal Penn State "19
GPA: 3.11
WE: Information Technology (Consulting)

Re: If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
09 Aug 2016, 23:33
1
This post was BOOKMARKED
Bunuel wrote: Given: \(xy\neq0\). Question: is \(x>y\) true?
(1) \(4x = 3y\) > if \(x\) and \(y\) are both positive, then \(x<y\) BUT if they are both negative then \(x>y\). Not sufficient. But from this statement we can grasp an important property we'll use while evaluating statements together: as \(xy\neq0\) then from statement (1) \(x\neq{y}\).
(2) \(yx=xy\). Now as LHS is absolute value, which is never negative, RHS must also be \(\geq0\) > so \(xy\geq0\) > then \(yx=(yx)\), and we'll get \((yx)=xy\) > \(0=0\), which is true. This means that equation \(yx=xy\) holds true when \(xy\geq0\) or, which is the same, when \(x\geq{y}\). But this not enough as \(x=y\) is still possible. Not sufficient.
(1)+(2) From (1) we got that \(x\neq{y}\) and from (2) \(x\geq{y}\), hence \(x>y\). Sufficient.
Answer: C.
Hope it helps. Hello Bunuel, Thank you for your answer. Although , as per mod property, isn't it the case that x = x when x>=0 and x when x<0 ? I would like to know why you are considering x = x when x<=0, because this is where the answer is really hinged on. Thanks!



Math Expert
Joined: 02 Sep 2009
Posts: 44592

Re: If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
10 Aug 2016, 00:58
ramblersm wrote: Bunuel wrote: Given: \(xy\neq0\). Question: is \(x>y\) true?
(1) \(4x = 3y\) > if \(x\) and \(y\) are both positive, then \(x<y\) BUT if they are both negative then \(x>y\). Not sufficient. But from this statement we can grasp an important property we'll use while evaluating statements together: as \(xy\neq0\) then from statement (1) \(x\neq{y}\).
(2) \(yx=xy\). Now as LHS is absolute value, which is never negative, RHS must also be \(\geq0\) > so \(xy\geq0\) > then \(yx=(yx)\), and we'll get \((yx)=xy\) > \(0=0\), which is true. This means that equation \(yx=xy\) holds true when \(xy\geq0\) or, which is the same, when \(x\geq{y}\). But this not enough as \(x=y\) is still possible. Not sufficient.
(1)+(2) From (1) we got that \(x\neq{y}\) and from (2) \(x\geq{y}\), hence \(x>y\). Sufficient.
Answer: C.
Hope it helps. Hello Bunuel, Thank you for your answer. Although , as per mod property, isn't it the case that x = x when x>=0 and x when x<0 ? I would like to know why you are considering x = x when x<=0, because this is where the answer is really hinged on. Thanks! 0 = 0 = 0, so you can include = sign in either of the cases: x = x, when x<=0 and x = x, when x >= 0.
_________________
New to the Math Forum? Please read this: Ultimate GMAT Quantitative Megathread  All You Need for Quant  PLEASE READ AND FOLLOW: 12 Rules for Posting!!! Resources: GMAT Math Book  Triangles  Polygons  Coordinate Geometry  Factorials  Circles  Number Theory  Remainders; 8. Overlapping Sets  PDF of Math Book; 10. Remainders  GMAT Prep Software Analysis  SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS)  Tricky questions from previous years.
Collection of Questions: PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests? Extrahard Quant Tests with Brilliant Analytics



Manager
Joined: 15 Oct 2017
Posts: 123

Re: If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
31 Jan 2018, 08:28
Bunuel wrote: Economist wrote: If xy ≠ 0, is x > y?
(1) 4x = 3y
(2) y  x = x  y This is a good one. +1 Economist for it. If xy ≠ 0, is x > y?Question asks whether \(x>y\)? (1) 4x = 3y > \(x=\frac{3}{4}y\), well this one is relatively easy. This statement only tells that x and y have the same sign. When they are both positive then \(x>y\), BUT when they are both negative \(y>x\). Not sufficient. (2) \(y  x = x  y\) > \(y  x = (yx)\). This means that \(y  x\leq{0}\) > \(x\geq{y}\). Thus, this statement says that x can be more than or equal to y. Not sufficient. (1)+(2) From (1) (\(x=\frac{3}{4}y\)) it follows that \(x\) is not equal to \(y\) (bearing in mind that xy ≠ 0), hence from (2): \(x>y\). Sufficient. Answer: C. For (1), isn't it the opposite? when both +ve x<y, when both ve x>y.



Senior Manager
Joined: 31 Jul 2017
Posts: 332
Location: Malaysia
WE: Consulting (Energy and Utilities)

Re: If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
31 Jan 2018, 08:36
urvashis09 wrote: Bunuel wrote: Economist wrote: If xy ≠ 0, is x > y?
(1) 4x = 3y
(2) y  x = x  y This is a good one. +1 Economist for it. If xy ≠ 0, is x > y?Question asks whether \(x>y\)? (1) 4x = 3y > \(x=\frac{3}{4}y\), well this one is relatively easy. This statement only tells that x and y have the same sign. When they are both positive then \(x>y\), BUT when they are both negative \(y>x\). Not sufficient. (2) \(y  x = x  y\) > \(y  x = (yx)\). This means that \(y  x\leq{0}\) > \(x\geq{y}\). Thus, this statement says that x can be more than or equal to y. Not sufficient. (1)+(2) From (1) (\(x=\frac{3}{4}y\)) it follows that \(x\) is not equal to \(y\) (bearing in mind that xy ≠ 0), hence from (2): \(x>y\). Sufficient. Answer: C. For (1), isn't it the opposite? when both +ve x<y, when both ve x>y. Yes but that doesn't change the answer anyway.
_________________
If my Post helps you in Gaining Knowledge, Help me with KUDOS.. !!



Intern
Joined: 04 Oct 2017
Posts: 40

If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
05 Feb 2018, 06:59
Kudos for the explanation. Am having trouble with absolute value and inequalities. How can I improve????



Math Expert
Joined: 02 Sep 2009
Posts: 44592

Re: If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y [#permalink]
Show Tags
05 Feb 2018, 07:10




Re: If xy 0, is x > y? (1) 4x = 3y (2) y  x = x  y
[#permalink]
05 Feb 2018, 07:10






