GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 19 Nov 2018, 10:21

Close

GMAT Club Daily Prep

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.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • How to QUICKLY Solve GMAT Questions - GMAT Club Chat

     November 20, 2018

     November 20, 2018

     09:00 AM PST

     10:00 AM PST

    The reward for signing up with the registration form and attending the chat is: 6 free examPAL quizzes to practice your new skills after the chat.
  • The winning strategy for 700+ on the GMAT

     November 20, 2018

     November 20, 2018

     06:00 PM EST

     07:00 PM EST

    What people who reach the high 700's do differently? We're going to share insights, tips and strategies from data we collected on over 50,000 students who used examPAL.

Does (x + a)^2 = y^2?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50670
Does (x + a)^2 = y^2?  [#permalink]

Show Tags

New post 15 Jan 2015, 06:02
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

77% (01:00) correct 23% (01:19) wrong based on 116 sessions

HideShow timer Statistics

Manager
Manager
User avatar
Joined: 22 Oct 2014
Posts: 88
Concentration: General Management, Sustainability
GMAT 1: 770 Q50 V45
GPA: 3.8
WE: General Management (Consulting)
Re: Does (x + a)^2 = y^2?  [#permalink]

Show Tags

New post 17 Jan 2015, 01:54
1
(1) We can subtract a from both sides of the equation and square it and we get to the equation in the question stem. So statement 1 is sufficient for any values x, y and a.

(2) This statement seems to contradict the equation in the question stem, so we are inclined to conclude that the statement is sufficient to answer the question. However, because the only equation we get is \((y+2a)^2=y^2\). However, there might be values for y and a that make the equation true. If a=0, then \((y+2a)^2=y^2\). This statement is therefore not sufficient.

Answer A.
_________________

\(\sqrt{-1}\) \(2^3\) \(\Sigma\) \(\pi\) ... and it was delicious!


Please consider giving +1 Kudos if deserved!

Intern
Intern
avatar
Joined: 27 Nov 2014
Posts: 49
Re: Does (x + a)^2 = y^2?  [#permalink]

Show Tags

New post 17 Jan 2015, 02:05
1
Does \((x + a)^2 = y^2\)?

(1) x = y - a
=> x=y-a
=> x-a=y
==> squaring both sides => \((x+a)^2 = y^2\) sufficient

(2) x = y + a

=> x-a=y
=> squaring both sides => \((x-a)^2 = y^2\) insufficient

Hence ans is A!

Regards
SG :wink:
Manager
Manager
avatar
Joined: 27 Oct 2013
Posts: 213
Location: India
Concentration: General Management, Technology
GMAT Date: 03-02-2015
GPA: 3.88
Re: Does (x + a)^2 = y^2?  [#permalink]

Show Tags

New post 17 Jan 2015, 06:18
Here we go -


St1: x = y - a

Q : (x + a)^2 = y^2
Substitute the value given in st1

( y - a + a)^2 = y ^ 2

Clearly statement 1 is sufficient

St2: x = y + a

Substitute
(y + 2a) ^ 2
No information is given about a...
so it may or may not be equal to y^2

Clearly option A is right
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6526
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: Does (x + a)^2 = y^2?  [#permalink]

Show Tags

New post 21 Nov 2017, 10:01
Bunuel wrote:
Does (x + a)^2 = y^2?

(1) x = y - a

(2) x = y + a

Kudos for a correct solution.



Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

The first step of VA(Variable Approach) method is modifying the original condition and the question, and rechecking the number of variables and the number of equations.
We can modify the original condition and question as follows.

\((x + a)^2 = y^2\)
\(⇔ (x + a)^2 - y^2 = 0\)
\(⇔ (x + a + y )(x+a-y) = 0\)
\(⇔ x = -y - a\) or \(x = y - a\)

Therefore, the condition 1) only is sufficient.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Manager
Manager
avatar
G
Joined: 20 Feb 2017
Posts: 166
Location: India
Concentration: Operations, Strategy
WE: Engineering (Other)
CAT Tests
Re: Does (x + a)^2 = y^2?  [#permalink]

Show Tags

New post 21 Nov 2017, 12:02
from Statement 1
x= y-a
so put the value in main equation
(x+a)^2
(Y-a+a)^2
Y^2
same as RHS
sufficient
from statement 2 :
x = y + a
put in the equation (x+a)^2=y^2
we will get (y+2a)^2
This can be equal to y^2 when a= 0
and for some values it will not be equal to Y^2
hence we get more than one possibility.
therefore insufficient.

answer : A
_________________

If you feel the post helped you then do send me the kudos (damn theya re more valuable than $)

GMAT Club Bot
Re: Does (x + a)^2 = y^2? &nbs [#permalink] 21 Nov 2017, 12:02
Display posts from previous: Sort by

Does (x + a)^2 = y^2?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.