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

It is currently 22 Feb 2019, 04:27

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 February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
  • Free GMAT RC Webinar

     February 23, 2019

     February 23, 2019

     07:00 AM PST

     09:00 AM PST

    Learn reading strategies that can help even non-voracious reader to master GMAT RC. Saturday, February 23rd at 7 AM PT
  • FREE Quant Workshop by e-GMAT!

     February 24, 2019

     February 24, 2019

     07:00 AM PST

     09:00 AM PST

    Get personalized insights on how to achieve your Target Quant Score.

What is the value of x?

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

Hide Tags

 
Manager
Manager
User avatar
G
Joined: 15 Dec 2015
Posts: 115
GMAT 1: 660 Q46 V35
GPA: 4
WE: Information Technology (Computer Software)
What is the value of x?  [#permalink]

Show Tags

New post 30 Aug 2017, 16:09
4
2
00:00
A
B
C
D
E

Difficulty:

  75% (hard)

Question Stats:

42% (01:21) correct 58% (01:27) wrong based on 157 sessions

HideShow timer Statistics

What is the value of x?

(1) \(\sqrt{x} = x-2\)

(2) x is not equal to 1.
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7334
Premium Member Reviews Badge
Re: What is the value of x?  [#permalink]

Show Tags

New post 30 Aug 2017, 19:12
3
1
DH99 wrote:
What is the value of x?

1. √ x = x-2

2. x is not equal to 1.



Hi..

1) √x=x-2
Square both sides
\(x=x^2-4x+4.....x^2-5x+4=0....x^2-4x-x+4=0.........(x-4)(x-1)=0\)
So x can be 4 or 1..
Substitute in equation and see if values are valid.
A) 2
√4=4-2=2.... Valid
B) 1
√1=1-2=-1..... Not valid
SQUARE Root has to be POSITIVE

Only possible value :- 4
Sufficient

2) X is not 1..
Nothing much.
But only to tempt you to click C....the C trap
Insufficient
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html


GMAT Expert

Manager
Manager
avatar
B
Joined: 06 Aug 2017
Posts: 85
GMAT 1: 570 Q50 V18
GMAT 2: 610 Q49 V24
GMAT 3: 640 Q48 V29
What is the value of x?  [#permalink]

Show Tags

New post 24 Sep 2017, 16:41
chetan2u wrote:
DH99 wrote:
What is the value of x?

1. √ x = x-2

2. x is not equal to 1.



Hi..

1) √x=x-2
Square both sides
\(x=x^2-4x+4.....x^2-5x+4=0....x^2-4x-x+4=0.........(x-4)(x-1)=0\)
So x can be 4 or 1..
Substitute in equation and see if values are valid.
A) 2
√4=4-2=2.... Valid
B) 1
√1=1-2=-1..... Not valid
SQUARE Root has to be POSITIVE

Only possible value :- 4
Sufficient

2) X is not 1..
Nothing much.
But only to tempt you to click C....the C trap
Insufficient


Thanks Chetan

Answer to this question teach us a very good lesson. Whenever we are doing squire on both the sides of the equation to solve it, always check putting the solution back into the equation to see if the value really satisfy the original equation.

For example, in this case by solving (by squiring both the sides) equation given in option 1, we get solution as 1 and 4, however putting back the value in the original equation clearly shows value=1 do not satisfy the original equation.

The reason for this is that for the simplicity we are doing squire on both the sides, but mathematically it produced a fundamentally different equation as compared to the original equation.
_________________

-------------------------------------------------------------------------------
Kudos are the only way to tell whether my post is useful.

GMAT PREP 1: Q50 V34 - 700

Veritas Test 1: Q43 V34 - 630
Veritas Test 2: Q46 V30 - 620
Veritas Test 3: Q45 V29 - 610
Veritas Test 4: Q49 V30 - 650

GMAT PREP 2: Q50 V34 - 700

Veritas Test 5: Q47 V33 - 650
Veritas Test 5: Q46 V33 - 650

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 9887
Premium Member
Re: What is the value of x?  [#permalink]

Show Tags

New post 16 Oct 2018, 09:32
Hello from the GMAT Club BumpBot!

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.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

GMAT Club Bot
Re: What is the value of x?   [#permalink] 16 Oct 2018, 09:32
Display posts from previous: Sort by

What is the value of x?

  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®.