Last visit was: 21 Jul 2024, 21:46 It is currently 21 Jul 2024, 21:46
Toolkit
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.

# Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1

SORT BY:
Tags:
Show Tags
Hide Tags
Math Expert
Joined: 02 Sep 2009
Posts: 94441
Own Kudos [?]: 642843 [22]
Given Kudos: 86716
Tutor
Joined: 17 Jul 2019
Posts: 1304
Own Kudos [?]: 1747 [1]
Given Kudos: 66
GMAT 1: 780 Q51 V45
GMAT 2: 780 Q50 V47
GMAT 3: 770 Q50 V45
General Discussion
Current Student
Joined: 13 Apr 2015
Posts: 1426
Own Kudos [?]: 4603 [2]
Given Kudos: 1228
Location: India
Retired Moderator
Joined: 29 Apr 2015
Posts: 717
Own Kudos [?]: 4234 [4]
Given Kudos: 302
Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE:Asset Management (Investment Banking)
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
3
Kudos
1
Bookmarks
Bunuel wrote:
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

1) Rewrite to get x = 1/y --> sufficient
2) Multiply by x to get x = 1/y --> sufficient

Manager
Joined: 13 Mar 2013
Posts: 135
Own Kudos [?]: 295 [0]
Given Kudos: 25
Location: United States
GPA: 3.5
WE:Engineering (Telecommunications)
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

From st 1
(1) xy = 1
there fore
x = 1/y

sufficient

From st 2
(2) 1/(xy) = 1

1/y = x ( simply rearranging the statement )

sufficient
hence D ans
Intern
Joined: 10 Jan 2017
Status:Don't watch the clock,Do what it does, Keep Going.
Posts: 18
Own Kudos [?]: 10 [0]
Given Kudos: 67
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
1 rewrite to get x=1/y sufficient
2 rewrite or multiply by x on both the sides you get x=1/y sufficient
D
GMAT Club Legend
Joined: 12 Sep 2015
Posts: 6804
Own Kudos [?]: 30846 [1]
Given Kudos: 799
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
1
Bookmarks
Top Contributor
Bunuel wrote:
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

Target question: Is x = 1/y?

Statement 1: xy = 1
This tells us that y does NOT equal 0 (and x does NOT equal 0 too)
So, if we take xy = 1 and divide both sides by y, we get x = 1/y
PERFECT, this is exactly what we are looking for.
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: 1/(xy) = 1
This tells us that x and y do NOT equal 0
So, we can take 1/(xy) and multiply both sides by x to get 1/y = x
Also PERFECT!
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Cheers,
Brent
Intern
Joined: 27 Dec 2018
Posts: 36
Own Kudos [?]: 13 [0]
Given Kudos: 10
Location: India
GPA: 3.48
WE:General Management (Manufacturing)
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Cross multiply the question and it becomes xy = 1
Now check the options
So both separately prove xy=1
Hence D

Intern
Joined: 17 Jan 2017
Posts: 17
Own Kudos [?]: 48 [0]
Given Kudos: 955
GMAT 1: 540 Q42 V23
GPA: 3.85
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Is there any problem for multiplying or dividing any variables without knowing the sign?? I found it in the inequality problem and now get confused. Please suggest me when to consider this principle?
GMAT Club Legend
Joined: 03 Jun 2019
Posts: 5318
Own Kudos [?]: 4241 [0]
Given Kudos: 161
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Bunuel wrote:
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

Is x = 1/y?

(1) xy = 1
x = 1/y
SUFFICIENT

(2) 1/(xy) = 1
x = 1/y
SUFFICIENT

IMO D
examPAL Representative
Joined: 07 Dec 2017
Posts: 1048
Own Kudos [?]: 1799 [0]
Given Kudos: 26
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
sajon wrote:
Is there any problem for multiplying or dividing any variables without knowing the sign?? I found it in the inequality problem and now get confused. Please suggest me when to consider this principle?

no - you just have to make sure you multiply both sides by the same thing.
There is a problem in inequalities - not in equations.
Current Student
Joined: 14 Oct 2014
Posts: 4
Own Kudos [?]: 5 [0]
Given Kudos: 5
Location: France
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
BrentGMATPrepNow wrote:
Bunuel wrote:
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

Target question: Is x = 1/y?

Statement 1: xy = 1
This tells us that y does NOT equal 0 (and x does NOT equal 0 too)
So, if we take xy = 1 and divide both sides by y, we get x = 1/y
PERFECT, this is exactly what we are looking for.
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: 1/(xy) = 1
This tells us that x and y do NOT equal 0
So, we can take 1/(xy) and multiply both sides by x to get 1/y = x
Also PERFECT!
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Cheers,
Brent

Thank you Brent! Why does it matter than neither x nor y equal 0?
Intern
Joined: 31 Oct 2020
Posts: 4
Own Kudos [?]: 0 [0]
Given Kudos: 1
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Bunuel wrote:
Is x = 1/y ?

(1) xy = 1
(2) 1/(xy) = 1

As per me, OA should be E as both statement are tautological (simply restating what is asked)

Posted from my mobile device
Math Expert
Joined: 02 Sep 2009
Posts: 94441
Own Kudos [?]: 642843 [0]
Given Kudos: 86716
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
sushil8891 wrote:
Bunuel wrote:
Is x = 1/y ?

(1) xy = 1
(2) 1/(xy) = 1

As per me, OA should be E as both statement are tautological (simply restating what is asked)

Posted from my mobile device

Yes, the statements are basically saying the same thing, but since each statement gives an YES answer to the question the answer is D, not E.
GMAT Club Legend
Joined: 08 Jul 2010
Status:GMAT/GRE Tutor l Admission Consultant l On-Demand Course creator
Posts: 6029
Own Kudos [?]: 13816 [0]
Given Kudos: 125
Location: India
GMAT: QUANT+DI EXPERT
Schools: IIM (A) ISB '24
GMAT 1: 750 Q51 V41
WE:Education (Education)
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Bunuel wrote:
Is x = 1/y ?

(1) xy = 1
(2) 1/(xy) = 1

Wanna make solving the Official Questions interesting???

Click here and solve 1000+ Official Questions with Video solutions as Timed Sectional Tests
and Dedicated Data Sufficiency (DS) Course

Video solution by GMATinsight

Get TOPICWISE: Concept Videos | Practice Qns 100+ | Official Qns 50+ | 100% Video solution CLICK HERE.
Two MUST join YouTube channels : GMATinsight (1000+ FREE Videos) and GMATclub
Target Test Prep Representative
Joined: 14 Oct 2015
Status:Founder & CEO
Affiliations: Target Test Prep
Posts: 19175
Own Kudos [?]: 22687 [0]
Given Kudos: 286
Location: United States (CA)
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Bunuel wrote:
Is x = 1/y ?

(1) xy = 1
(2) 1/(xy) = 1

Solution:

Question Stem Analysis:

We need to determine whether x = 1/y.

Statement One Alone:

Dividing both sides by y (since y can’t be 0), we have x = 1/y. Statement one alone is sufficient.

Statement Two Alone:

Multiplying both sides by xy (since xy can’t be 0), we have xy = 1. Since this is the same as statement one and statement one is sufficient, statement two is also sufficient.

Non-Human User
Joined: 09 Sep 2013
Posts: 34041
Own Kudos [?]: 853 [0]
Given Kudos: 0
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#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.
Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink]
Moderator:
Math Expert
94441 posts