Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

I am confused with the answer; and the explanation as well.

My answer is D.

Because, in statement 1, if we add y^2 on both sides, we get x^2 = y^2. Then, if we square root both the sides of the equation, we get x = y (no matter whether they are positive or negative). So, this is sufficient and is eliminating option B, C, and E.

Then, in the statement 2, if we square root both the sides of the equation, we get x - y = 0, or x = y (no matter whether they are positive or negative).

Therefore, my answer is D. However, Kaplan Premier 2011 shows the answer as B and explains it thereby.

square root of x^2 = could be x or -x ( not just x)

in other words square root of x^2 = |x| = +-x

so when you take square root on both sides , you will have +- on both sides. not enough to find the sign of the variable.

=> x = y or x = -y

Eg: \sqrt{(x^2)} = 25 => |x| = 5 =>x = +5 or -5

Hope it helps.

Schawjibb wrote:

@ Shubhabsh Da'

I am confused with the answer; and the explanation as well.

My answer is D.

Because, in statement 1, if we add y^2 on both sides, we get x^2 = y^2. Then, if we square root both the sides of the equation, we get x = y (no matter whether they are positive or negative). So, this is sufficient and is eliminating option B, C, and E.

Then, in the statement 2, if we square root both the sides of the equation, we get x - y = 0, or x = y (no matter whether they are positive or negative).

Therefore, my answer is D. However, Kaplan Premier 2011 shows the answer as B and explains it thereby.

I found this question in Kaplan Premier 2011. I am confused with their answer and its explanation (or, may be I am wrong). Can anyone come up with an answer supported by precise explanation?

Q. Does x = y? (1) x^2 - y^2 = 0 (2) (x - y)^2 = 0

Thanks in advance!

Solution: Statement 1: \(x^2-y^2=0\) \(x^2=y^2\) Squaring both sides, would result to two solutions: x= y OR x=-y. So, INSUFFICIENT!

Statement 2: \((x-y)^2=0\) To get a 0, x-y must be equal to 0. \(x=y\) SUFFICIENT!

Could you please help me in one regard? I need a resource (book/forum discussion) from where I can really learn how to solve a DS problem systematically and in minimum time.

Background: I have started going through the DS section from Kaplan Premier 2011 yesterday. And the result of yesterday's (first-time) practice was devastating. 13 out of 20 were incorrect. And no question was answered in less than 2 minutes! I am just drowning into frustration.......

My 2 cents on this.

See the best resources are the OG's, GMAT Club Math Forum and the MGMAT tests.

Seeing the problem that you are facing right now,probably you should brush up your basics first.Then start with OG and subsequently move on to higher difficulty level numerical s.
_________________

Visit -- http://www.sustainable-sphere.com/ Promote Green Business,Sustainable Living and Green Earth !!

Thanks a lot! I think my basic problem pertaining to DS is with Number Properties. Because, in other fields I feel myself comfortable as long as the math part is concerned. Do you think MGMAT Number Properties book will suffice? Suggestions are highly appreciated?

Re: Does x = y? (1) x^2 - y^2 = 0 (2) (x - y)^2 = 0 [#permalink]

Show Tags

15 Oct 2013, 09:31

Schawjibb wrote:

I found this question in Kaplan Premier 2011. I am confused with their answer and its explanation (or, may be I am wrong). Can anyone come up with an answer supported by precise explanation?

Q. Does x = y? (1) x^2 - y^2 = 0 (2) (x - y)^2 = 0

Thanks in advance!

Hi there, let me take a bite a this one.

So does x = y?

From Statement 1:

x^2 - y^2 = 0

This means that Abs (X) = Abs (Y) But could be that x = -y, or x = y Hence Insuff

From Statement 2

(x-y)^2 = 0 (x-y) = 0 So x = y Suff

Answer is B

Cheers J

Last edited by jlgdr on 15 Oct 2013, 10:09, edited 1 time in total.

I found this question in Kaplan Premier 2011. I am confused with their answer and its explanation (or, may be I am wrong). Can anyone come up with an answer supported by precise explanation?

Q. Does x = y? (1) x^2 - y^2 = 0 (2) (x - y)^2 = 0

Thanks in advance!

Hi there, let me take a bite a this one.

So does x = y?

From Statement 1:

x^2 - y^2 = 0

This means that Abs (X) = Abs (Y) But could be that x = -y, or x = y Hence Insuff

From Statement 2

(x-y)^2 = 0 (x+y)(x-y) = 0 x = -y or x = y So Insuff

From Statements 1 and 2 together: We have exactly the same information, hence IMHO E is the correct answer

Cheers J

That's not correct.

Does x = y?

(1) x^2 - y^2 = 0 --> x^2=y^2 --> x=y or x=-y. Not sufficient.

Re: Does x = y? (1) x^2 - y^2 = 0 (2) (x - y)^2 = 0 [#permalink]

Show Tags

15 Oct 2013, 10:08

Bunuel wrote:

jlgdr wrote:

Schawjibb wrote:

I found this question in Kaplan Premier 2011. I am confused with their answer and its explanation (or, may be I am wrong). Can anyone come up with an answer supported by precise explanation?

Q. Does x = y? (1) x^2 - y^2 = 0 (2) (x - y)^2 = 0

Thanks in advance!

Hi there, let me take a bite a this one.

So does x = y?

From Statement 1:

x^2 - y^2 = 0

This means that Abs (X) = Abs (Y) But could be that x = -y, or x = y Hence Insuff

From Statement 2

(x-y)^2 = 0 (x+y)(x-y) = 0 x = -y or x = y So Insuff

From Statements 1 and 2 together: We have exactly the same information, hence IMHO E is the correct answer

Cheers J

That's not correct.

Does x = y?

(1) x^2 - y^2 = 0 --> x^2=y^2 --> x=y or x=-y. Not sufficient.

(2) (x - y)^2 = 0 --> x-y=0 --> x=y. Sufficient.

Answer: B.

Apologies for that. Yes that's in fact correct. Thanks for pointing out. Cheers J

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

There’s something in Pacific North West that you cannot find anywhere else. The atmosphere and scenic nature are next to none, with mountains on one side and ocean on...

This month I got selected by Stanford GSB to be included in “Best & Brightest, Class of 2017” by Poets & Quants. Besides feeling honored for being part of...

Joe Navarro is an ex FBI agent who was a founding member of the FBI’s Behavioural Analysis Program. He was a body language expert who he used his ability to successfully...