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

It is currently 17 Jan 2019, 16:10

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 January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
  • The winning strategy for a high GRE score

     January 17, 2019

     January 17, 2019

     08:00 AM PST

     09:00 AM PST

    Learn the winning strategy for a high GRE score — what do people who reach a high score do differently? We're going to share insights, tips and strategies from data we've collected from over 50,000 students who used examPAL.
  • Free GMAT Strategy Webinar

     January 19, 2019

     January 19, 2019

     07:00 AM PST

     09:00 AM PST

    Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.

If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0

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

Hide Tags

 
Senior SC Moderator
User avatar
V
Joined: 14 Nov 2016
Posts: 1323
Location: Malaysia
GMAT ToolKit User Premium Member
If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0  [#permalink]

Show Tags

New post 09 Mar 2017, 21:30
4
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

33% (03:00) correct 67% (02:48) wrong based on 63 sessions

HideShow timer Statistics

If \(b<0\), is \(5b(a+b)>-a^2-b^2\)? 

1) \(a+2b>0\)

2) \(a+3b>0\)

_________________

"Be challenged at EVERY MOMENT."

“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

Rules for posting in verbal forum | Please DO NOT post short answer in your post!

Advanced Search : https://gmatclub.com/forum/advanced-search/

Senior SC Moderator
User avatar
V
Joined: 14 Nov 2016
Posts: 1323
Location: Malaysia
GMAT ToolKit User Premium Member
Re: If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0  [#permalink]

Show Tags

New post 03 Apr 2017, 15:48
1
2
ziyuen wrote:
If \(b<0\), is \(5b(a+b)>-a^2-b^2\)? 

1) \(a+2b>0\)

2) \(a+3b>0\)


OFFICIAL EXPLANATION


You need preliminary knowledge to solve this question.

If b<0, you get -3b>-2b>-b. If you take the 1st step of the variable approach and modify the original condition and the question,
Que: is 5b(a+b) > -a^2-b^2 → 5ab+5b2+a^2+b^2>0, a^2+5ab+6b^2>0, or (a+3b)(a+2b)>0

In the original condition, there are 2 variables (a, b) and 1 equation (b<0), and in order to match the number of variables to the number of equations, there must be 1 more equation. Therefore, D is most likely to be the answer.

In the case of con 1), a>-2b, so (a, b) = (3,-1) no, and (a, b) = (5,-1) yes, hence it is not sufficient.

In the case of con 2), a>-3b>-2b. This is because b<0, and it is shown in the preliminary knowledge above. If so, a>-3b and a>-2b, then a+3b>0 and a+2b>0. Since (a+3b)(a+2b)>0 is always yes, it is sufficient. The answer is B.
_________________

"Be challenged at EVERY MOMENT."

“Strength doesn’t come from what you can do. It comes from overcoming the things you once thought you couldn’t.”

"Each stage of the journey is crucial to attaining new heights of knowledge."

Rules for posting in verbal forum | Please DO NOT post short answer in your post!

Advanced Search : https://gmatclub.com/forum/advanced-search/

Intern
Intern
avatar
Joined: 09 Jan 2017
Posts: 6
Re: If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0  [#permalink]

Show Tags

New post 04 Apr 2017, 00:29
Can someone explain this more easily? Don't get it at all.
Manager
Manager
avatar
S
Joined: 25 Apr 2016
Posts: 59
CAT Tests
If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0  [#permalink]

Show Tags

New post 04 Apr 2017, 00:51
after factorizing the inequality would boils down to (2b+a)(a+3b)>0 and as "b"<0, the solution for the inequality would be a>-2b or a<-3b. Try consider b=-1, now, the 1st statement says a>-2 and that to me is sufficient and not to mention that 2nd statement would clearly be ambiguous as the solution suggest. -> for me it's A
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 9419
Premium Member
Re: If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0  [#permalink]

Show Tags

New post 26 Jul 2018, 05:52
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: If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0 &nbs [#permalink] 26 Jul 2018, 05:52
Display posts from previous: Sort by

If b<0, is 5b(a+b)>-a^2-b^2? 1) a+2b>0 2) a+3b>0

  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®.