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

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Bunuel
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Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  21 Oct 2015, 20:33
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Quiz Dashboard Attempt only this question Same topic and source Same topic and difficulty Same source and difficulty Random Chronological Reverse chronological Learn more
00:00
A
B
C
D
E

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5% (low)

Question Stats:

93% (00:32) correct 7% (00:46) wrong based on 2450 sessions

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Is x = 1/y ?

(1) xy = 1
(2) 1/(xy) = 1
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  25 Oct 2020, 18:01
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  21 Oct 2015, 22:12
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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
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  23 Oct 2015, 00:15
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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

Answer D
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  23 Oct 2015, 19:41
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
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  18 Sep 2017, 01:26
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
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  10 Oct 2017, 07:54
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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

Answer:
Show Spoiler
D


Cheers,
Brent
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  11 Jan 2019, 02:05
Cross multiply the question and it becomes xy = 1
Now check the options
So both separately prove xy=1
Hence D

Kudos please
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  31 May 2019, 04:07
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?
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  16 Sep 2019, 02:19
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
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  16 Sep 2019, 03:43
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.
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  03 Nov 2020, 06:04
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

Answer:
Show Spoiler
D


Cheers,
Brent


Thank you Brent! Why does it matter than neither x nor y equal 0?
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sushil8891
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  11 Nov 2020, 13:51
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)

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Bunuel
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  11 Nov 2020, 13:55
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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.
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  06 May 2021, 09:49
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Bunuel wrote:
Is x = 1/y ?

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


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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  08 May 2021, 09:59
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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.

Answer: D
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