Last visit was: 24 Apr 2024, 23:15 It is currently 24 Apr 2024, 23:15

Close
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
Your Progress

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.
Close
Request Expert Reply
Confirm Cancel
SORT BY:
Date
Tags:
Difficulty: 505-555 Levelx   Algebrax                        
Show Tags
Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 92900
Own Kudos [?]: 618860 [43]
Given Kudos: 81588
Send PM
Most Helpful Reply
Math Expert
Joined: 02 Sep 2009
Posts: 92900
Own Kudos [?]: 618860 [15]
Given Kudos: 81588
Send PM
General Discussion
avatar
SVP
SVP
Joined: 27 Dec 2012
Status:The Best Or Nothing
Posts: 1562
Own Kudos [?]: 7208 [1]
Given Kudos: 193
Location: India
Concentration: General Management, Technology
WE:Information Technology (Computer Software)
Send PM
User avatar
Intern
Intern
Joined: 26 Jan 2015
Posts: 7
Own Kudos [?]: 8 [0]
Given Kudos: 6
Send PM
Re: If (x + y)/(xy) = 1, then y = [#permalink]
Bunuel wrote:
SOLUTION

If (x + y)/(xy) = 1, then y =

(A) x/(x - 1)
(B) x/(x + 1)
(C) (x - 1)/x
(D) (x + 1)/x
(E) x

\(\frac{x + y}{xy} = 1\);

\(x + y = xy\);

\(x = xy-y\);

\(x = y(x-1)\);

\(y=\frac{x}{x-1}\).

Answer: A.



Could you please explain the last step ? i.e. how you got from x= y(x-1) to your solution?!

Yo divided x by y and then you got x/y=(x-1) and how do you get the x over now ?
Math Expert
Joined: 02 Sep 2009
Posts: 92900
Own Kudos [?]: 618860 [1]
Given Kudos: 81588
Send PM
Re: If (x + y)/(xy) = 1, then y = [#permalink]
1
Kudos
Expert Reply
sauberheine1 wrote:
Bunuel wrote:
SOLUTION

If (x + y)/(xy) = 1, then y =

(A) x/(x - 1)
(B) x/(x + 1)
(C) (x - 1)/x
(D) (x + 1)/x
(E) x

\(\frac{x + y}{xy} = 1\);

\(x + y = xy\);

\(x = xy-y\);

\(x = y(x-1)\);

\(y=\frac{x}{x-1}\).

Answer: A.



Could you please explain the last step ? i.e. how you got from x= y(x-1) to your solution?!

Yo divided x by y and then you got x/y=(x-1) and how do you get the x over now ?


Divide both parts of \(x = y(x-1)\) by x-1 to get \(\frac{x}{x-1}=y\).
User avatar
Manager
Manager
Joined: 05 Jul 2015
Posts: 53
Own Kudos [?]: 187 [0]
Given Kudos: 3
Concentration: Real Estate, International Business
GMAT 1: 600 Q33 V40
GPA: 3.3
Send PM
Re: If (x + y)/(xy) = 1, then y = [#permalink]
I had a very strange way of solving this. Might not always work.

I plugged in numbers and already wasted enough time trying to figure out which numbers to plug in that I didn't want to go back and solve algebraically.

So what numbers added to each other and divided by the product of each other equals 1? The only ones I could think of included 0 making the solution undefined. X=1 Y=0 ...... Answer A is also Undefined while all the others give some sort of solution.

Warning: I suck at math so take my advice with a grain of salt.
GMAT Club Legend
GMAT Club Legend
Joined: 19 Dec 2014
Status:GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Posts: 21846
Own Kudos [?]: 11665 [0]
Given Kudos: 450
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Send PM
Re: If (x + y)/(xy) = 1, then y = [#permalink]
Expert Reply
Hi DJ1986,

This question is a type of 'in terms of' question - the prompt gives you an equation and asks you to isolate one of the variables 'in terms of' the other variable(s) in the equation. These types of questions are typically best solved with Algebra (TESTing VALUES can get complicated and you might not easily find values that 'fit' the given equation.

To answer your question though, X=2, Y=2 gives us (2+2)/(2)(2) = 1. Using those values would lead us to 2 answers though (Answers A and E).

GMAT assassins aren't born, they're made
Rich
Target Test Prep Representative
Joined: 14 Oct 2015
Status:Founder & CEO
Affiliations: Target Test Prep
Posts: 18756
Own Kudos [?]: 22049 [0]
Given Kudos: 283
Location: United States (CA)
Send PM
Re: If (x + y)/(xy) = 1, then y = [#permalink]
Expert Reply
Quote:

If (x + y)/(xy) = 1, then y =

(A) x/(x - 1)
(B) x/(x + 1)
(C) (x - 1)/x
(D) (x + 1)/x
(E) x


We can simplify the given equation:

(x + y)/(xy) = 1

x + y = xy

x = xy - y

x = y(x - 1)

x/(x - 1) = y

Answer: A
Senior Manager
Senior Manager
Joined: 16 Nov 2021
Posts: 476
Own Kudos [?]: 27 [0]
Given Kudos: 5900
Location: United Kingdom
Send PM
Re: If (x + y)/(xy) = 1, then y = [#permalink]
ScottTargetTestPrep wrote:
Quote:

If (x + y)/(xy) = 1, then y =

(A) x/(x - 1)
(B) x/(x + 1)
(C) (x - 1)/x
(D) (x + 1)/x
(E) x


We can simplify the given equation:

(x + y)/(xy) = 1

x + y = xy

x = xy - y

x = y(x - 1)

x/(x - 1) = y

Answer: A


Thanks ScottTargetTestPrep, to clarify at this stage x + y = xy, y = xy-x , y = x(y-1) would have been correct too right if it's in the answer choice? Thanks
User avatar
Non-Human User
Joined: 09 Sep 2013
Posts: 32661
Own Kudos [?]: 821 [0]
Given Kudos: 0
Send PM
Re: If (x + y)/(xy) = 1, then y = [#permalink]
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
GMAT Club Bot
Re: If (x + y)/(xy) = 1, then y = [#permalink]
Moderators:
Math Expert
92900 posts
Senior Moderator - Masters Forum
3137 posts

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