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Is |x| = |y|? (1) x = -y (2) x^2 = y^2

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Is |x| = |y|? (1) x = -y (2) x^2 = y^2  [#permalink]

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New post Updated on: 11 Nov 2017, 01:25
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Question Stats:

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Is |x| = |y|?

(1) x = -y
(2) x^2 = y^2

I found this question in GMAT Prep and selected ST2 as the answer but that's wrong.

Normally, x^2 would equal to lxl since it will contain both signs "positive as well as negative". How come st 1 is true?

Does it assume that since +x = -y, it must be true that -x is also equal to -y or?

What am I missing? :(

Thanks for your hep!

Originally posted by HarveyKlaus on 16 Dec 2015, 07:06.
Last edited by Bunuel on 11 Nov 2017, 01:25, edited 3 times in total.
Formatted the question.
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Re: Is |x| = |y|? (1) x = -y (2) x^2 = y^2  [#permalink]

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New post 10 Nov 2017, 17:20
5
You are asked whether |x|=|y| or in other words, is the distance of x from 0 = distance of y from 0 ? You would get a yes if x= y or x=-y. Lets evaluate the choices.

Per statement 1:x=−yx=−y . Clearly this is one of the conditions we are looking for. Assume 2-3 different values. x=2, y = -2 --> 2 and -2 are both 2 units from 0 . Similar for 3/-3 or 10/-10 etc. Thus this statement is sufficient.

Per statement 2: x2=y2x2=y2 ---> x=±yx=±y. Again both the cases, x=y and x=-y give you a "yes" for the question asked as is hence sufficient.

Both statements are sufficient ---> D is the correct answer.
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Re: Is |x| = |y|? (1) x = -y (2) x^2 = y^2  [#permalink]

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New post 16 Dec 2015, 07:38
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HarveyKlaus wrote:
Is lxl = lyl ?

A) x=-y
b) x^2 = y^2

I found this question in GMAT Prep and selected ST2 as the answer but that's wrong.

Normally, x^2 would equal to lxl since it will contain both signs "positive as well as negative". How come st 1 is true?

Does it assume that since +x = -y, it must be true that -x is also equal to -y or?

What am I missing? :(

Thanks for your hep!


You are asked whether |x|=|y| or in other words, is the distance of x from 0 = distance of y from 0 ? You would get a yes if x= y or x=-y. Lets evaluate the choices.

Per statement 1:\(x=-y\) . Clearly this is one of the conditions we are looking for. Assume 2-3 different values. x=2, y = -2 --> 2 and -2 are both 2 units from 0 . Similar for 3/-3 or 10/-10 etc. Thus this statement is sufficient.

Per statement 2: \(x^2=y^2\) ---> \(x= \pm y\). Again both the cases, x=y and x=-y give you a "yes" for the question asked as is hence sufficient.

Both statements are sufficient ---> D is the correct answer.
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Re: Is |x| = |y|? (1) x = -y (2) x^2 = y^2  [#permalink]

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New post 17 Dec 2015, 06:54
statement 1 is sufficient as absolute value for -ve should give +ve
statement 2 is sufficient as
it will give either x and y both are +ve or both are -ve
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Re: Is |x| = |y|? (1) x = -y (2) x^2 = y^2  [#permalink]

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New post 09 Mar 2018, 03:18
HarveyKlaus wrote:
Is |x| = |y|?

(1) x = -y
(2) x^2 = y^2

I found this question in GMAT Prep and selected ST2 as the answer but that's wrong.

Normally, x^2 would equal to lxl since it will contain both signs "positive as well as negative". How come st 1 is true?

Does it assume that since +x = -y, it must be true that -x is also equal to -y or?

What am I missing? :(

Thanks for your hep!


Question:

Is |x| = |y|?

This can be represented in few ways as follow:

1. x = y

2. x = -y

3. -x = y

4. -x = -y

5. x^2 = y^2

If we can have any of these conditions, answer will be YES.

St 1: x = -y (Second condition) Sufficient

St 2: x^2 = y^2 (Fifth condition) Sufficient

(D)
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Re: Is |x| = |y|? (1) x = -y (2) x^2 = y^2 &nbs [#permalink] 09 Mar 2018, 03:18
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