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What is the value of x^2  y^2?
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20 Oct 2013, 06:32
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What is the value of x^2  y^2? (1) x + y = 2x (2) x  y = 0
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Re: What is the value of x^2  y^2?
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20 Oct 2013, 06:36
What is the value of x^2  y^2?
\(x^2  y^2=(xy)(x+y)\)
(1) x + y = 2x > rearrange: \(xy=0\) > \((xy)(x+y)=0\). Sufficient.
(2) x  y = 0 > \(xy=0\) > \((xy)(x+y)=0\). Sufficient.
Answer: D.




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Re: What is the value of x^2  y^2?
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27 May 2014, 09:11
Bunnuel, I have a hard time getting my approach clear on problems like that.
What made you rearrange statement (1) and not insert it in the q stem such as (2x)(x+y)?



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Re: What is the value of x^2  y^2?
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28 May 2014, 04:59
steilbergauf wrote: Bunnuel, I have a hard time getting my approach clear on problems like that.
What made you rearrange statement (1) and not insert it in the q stem such as (2x)(x+y)? Seems natural to rearrange and simplify \(x + y = 2x\) to get \(x  y = 0\) or \(x=y\). If you substitute it leads nowhere.



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Re: What is the value of x^2  y^2?
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28 May 2014, 12:37
It's a good habit to combine like terms when possible to make sure you are getting what the equation is really telling you. If x appears on both sides of the equation, there is room to simplify!
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Re: What is the value of x^2  y^2?
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28 May 2014, 12:48
DmitryFarber wrote: It's a good habit to combine like terms when possible to make sure you are getting what the equation is really telling you. If x appears on both sides of the equation, there is room to simplify! Thank you. That makes sense! Cheers...



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Re: What is the value of x^2  y^2?
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29 May 2014, 03:26
(1) x+y=2x We know that x+x=2x, so it is obvious that x=y and x^2y^2=0 SUFFICIENT
(2) xy=0 Rearranging this, we get x=y, so again x^2y^2=0 SUFFICIENT
Answer is D
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Re: What is the value of x^2  y^2?
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19 Jul 2016, 09:13
Hi, I am quite lost on this one...to get (1) x + y = 2x, why it breaks up to (x−y)(x+y)=0 and not (x−y)(x+y)=2x.
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Re: What is the value of x^2  y^2?
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19 Jul 2016, 09:16
sony1000 wrote: Hi, I am quite lost on this one...to get (1) x + y = 2x, why it breaks up to (x−y)(x+y)=0 and not (x−y)(x+y)=2x. x + y = 2x Rearrange: x  y = 0.



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Re: What is the value of x^2  y^2?
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20 Aug 2016, 17:27
steilbergauf wrote: Bunnuel, I have a hard time getting my approach clear on problems like that.
What made you rearrange statement (1) and not insert it in the q stem such as (2x)(x+y)? That's exactly what I did and got this wrong. I incorrectly solved this within 20 seconds: 10 seconds on each stem. I should've spent more time since it was way too easy.



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Re: What is the value of x^2  y^2?
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15 Jun 2017, 09:33
steilbergauf wrote: Bunnuel, I have a hard time getting my approach clear on problems like that.
What made you rearrange statement (1) and not insert it in the q stem such as (2x)(x+y)? well you just have to recognise that we are dealing with a differences of squares, thats it. x^2y^2 = (xy) (x+y) Even if you get statement one wrong, statement 2 will safe your ass For instance: (1) x+y=2x lets say insufficient (2) xy=0 now you should recognise where this is going, so lets go back to (1) x+y=2x 0 = 2xxy 0 = xy> sufficient
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Re: What is the value of x^2  y^2?
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16 Jul 2017, 11:37
bulletpoint wrote: What is the value of x^2  y^2?
(1) x + y = 2x (2) x  y = 0 The goal is to find the unique value equal to x^2y^2. Statement 1) x+y = 2x x+y=2x x=y xy=0 x^2y^2 = (x+y)(xy) (x+y)*0 =0 Sufficient. Statement 2) xy = 0 x^2y^2 =(x+y)*(xy) (x+y)*0 = 0 Sufficient.



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Re: What is the value of x^2  y^2?
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26 Aug 2018, 23:43
Ix x < 0?
1. x5 = 7x+2 2. x+5 = 4x+5



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Re: What is the value of x^2  y^2?
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27 Aug 2018, 00:04
anushilaghosh wrote: Ix x < 0?
1. x5 = 7x+2 2. x+5 = 4x+5 Hi anushilaghosh, I would request to post the question in DS forum. You may go through the below links that will guide you: https://gmatclub.com/forum/howtomake ... 47089.htmlhttps://gmatclub.com/forum/rulesforpo ... l#p1092822
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Re: What is the value of x^2  y^2?
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07 Feb 2019, 08:06
bulletpoint wrote: What is the value of x^2  y^2?
(1) x + y = 2x (2) x  y = 0 Overthinking marks such questions incorrect from 1) x + y = 2x x  y = 0 (xy) (x+y) = 0 from 2 xy =0 (xy) (x+y) = 0 D
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What is the value of x^2  y^2?
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07 Feb 2019, 08:13
anushilaghosh wrote: Ix x < 0?
1. x5 = 7x+2 2. x+5 = 4x+5 This question is discussed here: https://gmatclub.com/forum/isx01x5 ... 16394.html It's flawed.



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Re: What is the value of x^2  y^2?
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04 May 2019, 14:10
For Statement I, I understand why x=y, but when you just subtract 2x from each side you get x+y=0 or yx=0, which is a different equation from the prompt's difference of squares equation, leading me to believe it is insufficient. Can someone help explain?



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Re: What is the value of x^2  y^2?
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04 May 2019, 17:49
nuvz wrote: For Statement I, I understand why x=y, but when you just subtract 2x from each side you get x+y=0 or yx=0, which is a different equation from the prompt's difference of squares equation, leading me to believe it is insufficient. Can someone help explain? Hi nuvz, You can always write yx=0 as (xy)=0 or, xy=0.
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Re: What is the value of x^2  y^2?
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