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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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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
1
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: ::
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: ::
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)

Posted from my mobile device
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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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DS: DS Standard deviation | Inequalities | 700+ GMAT Data Sufficiency Questions With Explanations | Tough and tricky exponents and roots questions | The Discreet Charm of the DS | Devil's Dozen!!! | Number Properties set | New DS set
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aamani02
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Re: Is x = 1/y? (1) xy = 1 (2) 1/(xy) = 1 [#permalink] New post  11 Nov 2020, 15:39
Bunuel wrote:
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.


But it doesn't say anything about y being zero or not, do we need to consider that 🤔
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