It is currently 22 May 2019, 15:22

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

x2−2xy+y2=0 and xy = 9.

Author Message
TAGS:
Manager
Joined: 27 Feb 2017
Posts: 189
Followers: 1

Kudos [?]: 53 [0], given: 15

x2−2xy+y2=0 and xy = 9. [#permalink]  11 Sep 2018, 12:56
00:00

Question Stats:

52% (00:53) correct 47% (01:09) wrong based on 17 sessions
$$x^2−2xy+y^2=0$$ and $$xy=9$$

 Quantity A Quantity B y 3

A. The quantity in Column A is greater
B. The quantity in Column B is greater
C. The two quantities are equal
D. The relationship cannot be determined from the information given

Official answer says D (Cannot be determined) but I strongly believe it is C (Quantities are equal)
[Reveal] Spoiler: OA

Last edited by Carcass on 11 Sep 2018, 14:43, edited 1 time in total.
Edited by Carcass
GRE Prep Club Legend
Joined: 07 Jun 2014
Posts: 4857
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 112

Kudos [?]: 1856 [1] , given: 397

Re: x2−2xy+y2=0 and xy = 9. [#permalink]  11 Sep 2018, 17:57
1
KUDOS
Expert's post
This is one of the questions you need to pay attention.

Given: $$x^2−2xy+y^2=0$$ or $$(x-y)^2=0$$ or $$x=y$$

Also given that $$xy=9$$, substituting value of x in terms of y or $$y^2=9$$ Here y can have 2 values 3 and -3.

Hence D is correct
_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Manager
Joined: 27 Feb 2017
Posts: 189
Followers: 1

Kudos [?]: 53 [0], given: 15

Re: x2−2xy+y2=0 and xy = 9. [#permalink]  11 Sep 2018, 18:04
sandy wrote:
This is one of the questions you need to pay attention.

Given: $$x^2−2xy+y^2=0$$ or $$(x-y)^2=0$$ or $$x=y$$

Also given that $$xy=9$$, substituting value of x in terms of y or $$y^2=9$$ Here y can have 2 values 3 and -3.

Hence D is correct

OHH!! The minus sign, I totally ignored that. Thanks, Sandy! I got confused with the explanation because it stated the combination of y= 9 or 1 as the reasoning, which did not fall in line with the given quadratic equation.
Re: x2−2xy+y2=0 and xy = 9.   [#permalink] 11 Sep 2018, 18:04
Display posts from previous: Sort by