Find all School-related info fast with the new School-Specific MBA Forum

It is currently 25 Oct 2014, 08:03

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Is it Ok to take the roots first?For example, in question 1

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 21 Aug 2010
Posts: 6
Followers: 0

Kudos [?]: 5 [0], given: 0

Is it Ok to take the roots first?For example, in question 1 [#permalink] New post 28 Aug 2010, 12:49
1
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 100% (00:14) wrong based on 2 sessions
Is it Ok to take the roots first?For example, in question 1 the roots for statement 1 are 0 and 5. For statement II, 0 and -5

Data sufficiency
1) Is X=5?

(I) x^2 – 5x = 0
(II)2x^2 + 10x= 0



2) Is x = y?

(I) |x-2|= 5
(II) y^2 – 4y – 21=0
Expert Post
1 KUDOS received
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23422
Followers: 3614

Kudos [?]: 28954 [1] , given: 2874

Re: DS Inequalities I [#permalink] New post 28 Aug 2010, 13:16
1
This post received
KUDOS
Expert's post
briandoldan wrote:
Is it Ok to take the roots first?For example, in question 1 the roots for statement 1 are 0 and 5. For statement II, 0 and -5

Data sufficiency
1) Is X=5?

(I) x^2 – 5x = 0
(II)2x^2 + 10x= 0



2) Is x = y?

(I) |x-2|= 5
(II) y^2 – 4y – 21=0


I'm not sure that I understand your question... But as for the problems:

Is x=5?

(1) x^2-5x=0 --> x=0 OR x=5. Not sufficient, to answer whether x=5.

(2) 2x^2+10x=0 --> x=0 OR x=-5. Here we know that x\neq{5}, hence sufficient.

Answer: B.

Is x = y?

(1) |x-2|= 5. Clearly insufficient as no info about y. But from this statement we know that either x=7 or x=-3.

(2) y^2-4y-21=0. Clearly insufficient as no info about x. But from this statement we know that either y=7 or y=-3.

(1)+(2) Now, it's possible that both x and y equal to -3 (or 7) and in this case answer would be YES: x=y BUT it's also possible x to be -3 and y to be 7 (or vise-versa) and in this case answer would be NO: x\neq{y}. Two different answers to the question, hence not sufficient.

Answer: E.

Hope it helps.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Intern
Intern
avatar
Joined: 21 Aug 2010
Posts: 6
Followers: 0

Kudos [?]: 5 [0], given: 0

Re: DS Inequalities I [#permalink] New post 28 Aug 2010, 13:23
Bunuel wrote:
briandoldan wrote:
Is it Ok to take the roots first?For example, in question 1 the roots for statement 1 are 0 and 5. For statement II, 0 and -5

Data sufficiency
1) Is X=5?

(I) x^2 – 5x = 0
(II)2x^2 + 10x= 0



2) Is x = y?

(I) |x-2|= 5
(II) y^2 – 4y – 21=0


I'm not sure that I understand your question... But as for the problems:

Is x=5?

(1) x^2-5x=0 --> x=0 OR x=5. Not sufficient, to answer whether x=5.

(2) 2x^2+10x=0 --> x=0 OR x=-5. Here we know that x\neq{5}, hence sufficient.

Answer: B.

Is x = y?

(1) |x-2|= 5. Clearly insufficient as no info about y. But from this statement we know that either x=7 or x=-3.

(2) y^2-4y-21=0. Clearly insufficient as no info about x. But from this statement we know that either y=7 or y=-3.

(1)+(2) Now, it's possible that both x and y equal to -3 (or 7) and in this case answer would be YES: x=y BUT it's also possible x to be -3 and y to be 7 (or vise-versa) and in this case answer would be NO: x\neq{y}. Two different answers to the question, hence not sufficient.

Answer: E.

Hope it helps.



Thanks a lot Bunuel. It helped a lot. =)

Regards
SVP
SVP
avatar
Joined: 17 Feb 2010
Posts: 1560
Followers: 12

Kudos [?]: 227 [0], given: 6

Re: DS Inequalities I [#permalink] New post 29 Aug 2010, 19:56
Bunuel, For the 1st question, I did not understand the highlighted part. How do we know that x is not equal to -5?


(2)2x^2 + 10x = 0 --> x = 0 or x = -5. [highlight]Here we know that x # 5[/highlight], hence sufficient
CEO
CEO
User avatar
Status: Nothing comes easy: neither do I want.
Joined: 12 Oct 2009
Posts: 2794
Location: Malaysia
Concentration: Technology, Entrepreneurship
Schools: ISB '15 (M)
GMAT 1: 670 Q49 V31
GMAT 2: 710 Q50 V35
Followers: 182

Kudos [?]: 989 [0], given: 235

Reviews Badge
Re: DS Inequalities I [#permalink] New post 29 Aug 2010, 20:02
seekmba wrote:
Bunuel, For the 1st question, I did not understand the highlighted part. How do we know that x is not equal to -5?


(2)2x^2 + 10x = 0 --> x = 0 or x = -5. [highlight]Here we know that x # 5[/highlight], hence sufficient


the question is : Is x = 5

(2)2x^2 + 10x = 0 --> x = 0 or x = -5.

=> x is not equal to 5. Hence it is sufficient to answer the question.
_________________

Fight for your dreams :For all those who fear from Verbal- lets give it a fight

Money Saved is the Money Earned :)

Jo Bole So Nihaal , Sat Shri Akaal

:thanks Support GMAT Club by putting a GMAT Club badge on your blog/Facebook :thanks

Get the best GMAT Prep Resources with GMAT Club Premium Membership

Gmat test review :
670-to-710-a-long-journey-without-destination-still-happy-141642.html

SVP
SVP
avatar
Joined: 17 Feb 2010
Posts: 1560
Followers: 12

Kudos [?]: 227 [0], given: 6

Re: DS Inequalities I [#permalink] New post 29 Aug 2010, 20:05
I got so lost in the options that completely forgot abt the original question. thats silly... thanks a bunch.
Re: DS Inequalities I   [#permalink] 29 Aug 2010, 20:05
    Similar topics Author Replies Last post
Similar
Topics:
Is it OK to take GMATPrep Repeatedly? smodak 7 16 Jul 2011, 10:11
Question on MGMAT SC example itsnotover 2 19 Jun 2011, 21:04
Question on roots chloeholding 3 30 Apr 2011, 19:20
Ok score but a lot of questions :) Darden2010 10 03 Dec 2007, 13:12
root question typicalgmatter 5 27 Dec 2006, 06:43
Display posts from previous: Sort by

Is it Ok to take the roots first?For example, in question 1

  Question banks Downloads My Bookmarks Reviews Important topics  


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

Powered by phpBB © phpBB Group and phpBB SEO

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®.