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Is x = 1/y?

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Is x = 1/y?  [#permalink]

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New post 21 Oct 2015, 21:33
4
1
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A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

92% (00:33) correct 8% (00:46) wrong based on 1239 sessions

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Re: Is x = 1/y?  [#permalink]

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New post 21 Oct 2015, 23:12
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?  [#permalink]

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New post 23 Oct 2015, 01:15
2
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?  [#permalink]

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New post 23 Oct 2015, 20:41
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?  [#permalink]

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New post 18 Sep 2017, 02:26
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?  [#permalink]

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New post 10 Oct 2017, 08:54
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1
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:

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Re: Is x = 1/y?  [#permalink]

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New post 11 Jan 2019, 03:05
Cross multiply the question and it becomes xy = 1
Now check the options
So both separately prove xy=1
Hence D

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Is x = 1/y?  [#permalink]

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New post 31 May 2019, 05:07
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?  [#permalink]

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New post 16 Sep 2019, 03:19
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?  [#permalink]

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New post 16 Sep 2019, 04:43
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?   [#permalink] 16 Sep 2019, 04:43
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