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

Question

Is x = 1/y ?

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

Kurtosis · Answer

Is x = 1/y ? --> Is x - (1/y) = 0 --> Is xy = 1 ?

St1: Sufficient
St2: (1/xy) - 1 = 0 --> 1 - xy = 0 --> xy = 1... Sufficient

Answer: D

reto · Answer

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

Answer D

TheKingInTheNorth · Answer

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

adil123 · Answer

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

BrentGMATPrepNow · Answer

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

Answer:  D

Cheers,
Brent

shahidomer77 · Answer

Cross multiply the question and it becomes xy = 1
Now check the options 
So both separately prove xy=1
Hence D

Kudos please

sajon · Answer

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?

Kinshook · Answer

Is x = 1/y?

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

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

IMO D

DavidTutorexamPAL · Answer

no - you just have to make sure you multiply both sides by the same thing. 
There is a problem in inequalities - not in equations.

avigutman · Answer

Video solution from Quant Reasoning:
 https://www.youtube.com/watch?v=iwPO94PUlLw

lucieparis · Answer

Thank you Brent! Why does it matter than neither x nor y equal 0?

sushil8891 · Answer

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

Posted from my mobile device

Bunuel · Answer

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.

GMATinsight · Answer

Answer: Option D

Video solution by  GMATinsight

https://www.youtube.com/watch?v=eLsiJOM4210

ScottTargetTestPrep · Answer

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.

Answer: D

bumpbot · Answer

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

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