GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 22 Oct 2019, 17:56 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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  R = 1 + 2xy + x^2y^2, what is the value of xy?

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

Hide Tags

Intern  Joined: 25 Sep 2010
Posts: 12
R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

3
25 00:00

Difficulty:   35% (medium)

Question Stats: 69% (01:22) correct 31% (01:51) wrong based on 555 sessions

HideShow timer Statistics

$$R = 1 + 2*x*y + x^2*y^2$$, what is the value of $$x*y$$?

(1) R = 0
(2) x > 0

Originally posted by satishreddy on 14 Oct 2010, 20:56.
Last edited by ENGRTOMBA2018 on 03 Sep 2015, 07:37, edited 3 times in total.
Formatted the question.
Math Expert V
Joined: 02 Sep 2009
Posts: 58427
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

5
7
satishreddy wrote:
R=1+2xy+x^2*y^2, what is the value of xy

1) R=0
2) x>0

OA : A

Question should be:

R=1+2xy+x^2*y^2, what is the value of xy?

(1) R=0 --> $$1+2xy+x^2*y^2=0$$ --> $$(xy+1)^2=0$$ --> $$xy=-1$$. Sufficient.
(2) x>0 --> Clearly insufficient.

 ! Please post PS questions in the PS subforum: gmat-problem-solving-ps-140/Please post DS questions in the DS subforum: gmat-data-sufficiency-ds-141/

_________________
General Discussion
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8027
GMAT 1: 760 Q51 V42 GPA: 3.82
R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

Forget conventional ways of solving math questions. In DS, Variable approach is

the easiest and quickest way to find the answer without actually solving the

problem. Remember equal number of variables and equations ensures a solution.

R=1+2xy+(xy)^2, what is the value of x∗y ?

(1) R = 0
(2) x > 0

==> transforming the original condition and the question by variable approach method, we have, R=(1+xy)^2, 1+xy=R, -R, then xy=R-1, xy=-R-1. if we know R we can find xy
In case of 1), if R=0 then xy=-1, a unique answer. Therefore it is sufficient. Thus A is the answer.
_________________
CEO  S
Joined: 20 Mar 2014
Posts: 2595
Concentration: Finance, Strategy
Schools: Kellogg '18 (M)
GMAT 1: 750 Q49 V44 GPA: 3.7
WE: Engineering (Aerospace and Defense)
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

1
1
MathRevolution wrote:
Forget conventional ways of solving math questions. In DS, Variable approach is

the easiest and quickest way to find the answer without actually solving the

problem. Remember equal number of variables and equations ensures a solution.

R=1+2xy+(xy)^2, what is the value of x∗y ?

(1) R = 0
(2) x > 0

==> transforming the original condition and the question by variable approach method, we have, R=(1+xy)^2, 1+xy=R, -R, then xy=R-1, xy=-R-1. if we know R we can find xy
In case of 1), if R=0 then xy=-1, a unique answer. Therefore it is sufficient. Thus A is the answer.

If you know our own innovative logics to find the answer, you don’t need to

actually solve the problem.
http://www.mathrevolution.com
- The one-and-only World’s First Variable Approach for DS and IVY Approach

for PS that allow anyone to easily solve GMAT math questions.

- The easy-to-use solutions. Math skills are totally irrelevant. Forget

conventional ways of solving math questions.

- The most effective time management for GMAT math to date allowing you to

solve 37 questions with 10 minutes to spare

- Hitting a score of 45 is very easy and points and 49-51 is also doable.

- We're offering 20% additional discounts to GMAT club members for "PS+DS" and

- Unlimited Access to over 120 free video lessons at

http://www.mathrevolution.com/gmat/lesson

Your actual solution is very difficult to find in the quoted post and your advertisement. Can you please reduce the size of your advertisement text? or better put it in your signatures. This way your posts will be useful for people in this forum.

Also, put the quoted post in proper formatting, so that your actual post is clearly visible.

Thanks
Intern  Joined: 24 Jan 2016
Posts: 18
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

R=1+2xy+x^2*y^2, what is the value of x∗y ?
(1) R = 0
(2) x > 0
R=1+2xy+x^2*y^2=(1+xy)^2
1- R=0 ⇒ 1+xy=0 ⇒ xy=-1 -- SUFFICIENT
2- x>0 -- Irrelevant
Director  G
Joined: 26 Oct 2016
Posts: 600
Location: United States
Concentration: Marketing, International Business
Schools: HBS '19
GMAT 1: 770 Q51 V44 GPA: 4
WE: Education (Education)
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

The answer is indeed A

R=1+2xy+x^2y^2 => (1+xy)^2

Statement I

R=0, therefore (1+xy)^2=0
xy=-1

Statement II
x>0

It does not gives us any specific value of x or y or R

Not Sufficient.

Hence A.
_________________
Thanks & Regards,
Anaira Mitch
Intern  B
Joined: 09 May 2016
Posts: 7
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

1st identify what is being asked, then looked for familiar structures (eg Quadratic equation when moving 1 to other side)
Director  D
Joined: 13 Mar 2017
Posts: 728
Location: India
Concentration: General Management, Entrepreneurship
GPA: 3.8
WE: Engineering (Energy and Utilities)
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

1
satishreddy wrote:
$$R = 1 + 2*x*y + x^2*y^2$$, what is the value of $$x*y$$?

(1) R = 0
(2) x > 0

$$R = 1 + 2xy + (x^2)(y^2)$$
$$R = 1 + (xy)^2$$
$$xy = \sqrt{R}-1$$

Statement 1: R=0
Surely it gives xy =-1
Sufficient

Statement 2: x>0
Irrelevant . Not Sufficient

_________________
CAT 2017 (98.95) & 2018 (98.91) : 99th percentiler
UPSC Aspirants : Get my app UPSC Important News Reader from Play store.

MBA Social Network : WebMaggu

Appreciate by Clicking +1 Kudos ( Lets be more generous friends.)

What I believe is : "Nothing is Impossible, Even Impossible says I'm Possible" : "Stay Hungry, Stay Foolish".
Manager  G
Status: On the journey of achieving
Affiliations: Senior Manager, CA by profession, CFA(USA) Level 2
Joined: 06 Feb 2016
Posts: 202
Location: India
Concentration: Finance, Finance
GMAT 1: 560 Q44 V21 GPA: 3.82
WE: Other (Commercial Banking)
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

Solving this question from statement 1 we get xy= -1 as (xy+1)^2 =0 which is sufficient
Statement 2 x>0, we cant find any value hence not suffice

Answer : Option A
_________________
Never Settle for something less than what you deserve...........

I've failed over and over and over again in my life and that is why I succeed--Michael Jordan
Kudos drives a person to better himself every single time. So Pls give it generously
Wont give up till i hit a 700+
Intern  B
Joined: 15 Feb 2019
Posts: 15
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

shashankism wrote:
satishreddy wrote:
$$R = 1 + 2*x*y + x^2*y^2$$, what is the value of $$x*y$$?

(1) R = 0
(2) x > 0

$$R = 1 + 2xy + (x^2)(y^2)$$
$$R = 1 + (xy)^2$$
$$xy = \sqrt{R}-1$$

Statement 1: R=0
Surely it gives xy =-1
Sufficient

Statement 2: x>0
Irrelevant . Not Sufficient

Please what happened to the 2xy in the question? I'm confused

Posted from my mobile device
Math Expert V
Joined: 02 Sep 2009
Posts: 58427
Re: R = 1 + 2xy + x^2y^2, what is the value of xy?  [#permalink]

Show Tags

Peachie wrote:
shashankism wrote:
satishreddy wrote:
$$R = 1 + 2*x*y + x^2*y^2$$, what is the value of $$x*y$$?

(1) R = 0
(2) x > 0

$$R = 1 + 2xy + (x^2)(y^2)$$
$$R = 1 + (xy)^2$$
$$xy = \sqrt{R}-1$$

Statement 1: R=0
Surely it gives xy =-1
Sufficient

Statement 2: x>0
Irrelevant . Not Sufficient

Please what happened to the 2xy in the question? I'm confused

Posted from my mobile device

There is a typo in that post. Should be:
$$R = 1 + 2xy + x^2y^2$$
$$R = 1 + 2xy + (xy)^2$$
$$R = (1 + xy)^2$$
_________________ Re: R = 1 + 2xy + x^2y^2, what is the value of xy?   [#permalink] 12 Jun 2019, 13:56
Display posts from previous: Sort by

R = 1 + 2xy + x^2y^2, what is the value of xy?

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne  