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

It is currently 22 Jan 2019, 02:29

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 winners of the GMAT game show

     January 22, 2019

     January 22, 2019

     10:00 PM PST

     11:00 PM PST

    In case you didn’t notice, we recently held the 1st ever GMAT game show and it was awesome! See who won a full GMAT course, and register to the next one.
  • Key Strategies to Master GMAT SC

     January 26, 2019

     January 26, 2019

     07:00 AM PST

     09:00 AM PST

    Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.

If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers

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

Hide Tags

 
Manager
Manager
User avatar
Status: struggling with GMAT
Joined: 06 Dec 2012
Posts: 123
Location: Bangladesh
Concentration: Accounting
GMAT Date: 04-06-2013
GPA: 3.65
If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers  [#permalink]

Show Tags

New post Updated on: 16 Dec 2012, 06:20
14
00:00
A
B
C
D
E

Difficulty:

  95% (hard)

Question Stats:

44% (02:44) correct 56% (02:26) wrong based on 215 sessions

HideShow timer Statistics

If \(\frac{(ab)^2+3ab-18}{(a-1)(a+2)}= 0\) where a and b are integers,which of the following could be the value of b?

I. 1
II. 2
III. 3

(A) I only
(B) II only
(C) I and II only
(D) I and III only
(E) I, II and III only

Originally posted by mun23 on 15 Dec 2012, 11:48.
Last edited by Bunuel on 16 Dec 2012, 06:20, edited 1 time in total.
Renamed the topic and edited the question.
Intern
Intern
User avatar
Joined: 24 Apr 2012
Posts: 48
Re: If \frac{(ab)^2+3ab-18}{(a-1)(a+2)}=0  [#permalink]

Show Tags

New post 16 Dec 2012, 03:22
3
1
Ans:

from the fraction we get that “a” cannot be 1 or -2, so putting the value of a in numerator we get the the values of “b” to 3,-6, -3/2 , therefore b cannot be 3 so the answer is (C).
_________________

www.mnemoniceducation.com

TURN ON YOUR MINDS!!!

Intern
Intern
avatar
Joined: 15 Aug 2012
Posts: 9
Re: If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers  [#permalink]

Show Tags

New post 16 Dec 2012, 06:29
From the Q,

Numerator = 0 whereas Denominator <> (cannot be) 0

Numerator = 0 provides: ab = -6 or ab = 3
Denominator <> 0 provides: a <> 1 and a <> -2

Put values of b in to ab to check for a:

1) b = 1; a = -6 or a = 3
2) b = 2; a = -3 or a = 3/2
3) b = 3; a = -2 or a = 1

But a <> 1 and a <> -2,

Hence, b can not be 3 and could be either 1 or 2.
Ans: C
Manager
Manager
User avatar
Joined: 24 Mar 2010
Posts: 64
Re: If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers  [#permalink]

Show Tags

New post 20 Dec 2012, 12:50
2
mun23 wrote:
If \(\frac{(ab)^2+3ab-18}{(a-1)(a+2)}= 0\) where a and b are integers,which of the following could be the value of b?

I. 1
II. 2
III. 3

(A) I only
(B) II only
(C) I and II only
(D) I and III only
(E) I, II and III only



For the \(\frac{(ab)^2+3ab-18}{(a-1)(a+2)}= 0\) = 0

numerator has to be zero
and a # 1 and a # -2 (Since these two values would make denominator zero and fraction undefined)

Now \((ab)^2+3ab-18\)

Put ab = x

\(x^2 + 3x - 18\)

factorized to

(x-3)(x+6)

Case I
x = ab = 3, => a =1 , b = 3 -- NOT POSSIBLE as we cannot have a = 1
x = ab = 3, => a =3 , b = 1 -- POSSIBLE

Case II
x = ab = -6, => a = -1, 2,+3,+6 & b = +2, -3, +6

Hence we can note that b can assume values 1 & 2 but not 3.

Hence C
_________________

- Stay Hungry, stay Foolish -

Veritas Prep GMAT Instructor
User avatar
D
Joined: 16 Oct 2010
Posts: 8804
Location: Pune, India
Re: If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers  [#permalink]

Show Tags

New post 20 Dec 2012, 20:25
mun23 wrote:
If \(\frac{(ab)^2+3ab-18}{(a-1)(a+2)}= 0\) where a and b are integers,which of the following could be the value of b?

I. 1
II. 2
III. 3

(A) I only
(B) II only
(C) I and II only
(D) I and III only
(E) I, II and III only


For \(\frac{(ab)^2+3ab-18}{(a-1)(a+2)}= 0\) to hold, \((ab)^2+3ab-18 = 0\)

You need 'a' to be an integer so put in the values of b to check whether you get integral values for 'a'
b = 1 => a^2 + 3a - 18 = 0 => (a + 6)(a - 3) = 0 => Integral values so acceptable
b = 2 => 4a^2 + 6a - 18 = 0 => (2a + 6)(2a - 3) = 0 => We get a = -3 (an integer) hence acceptable
b = 3 => 9a^2 + 9a - 18 = 0 => (a + 2)(a - 1) = 0 => We get a = -2 or 1. a can take neither of these values since they make the denominator 0. Not acceptable

Answer (C)
_________________

Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >

Manager
Manager
User avatar
S
Joined: 23 Jan 2016
Posts: 187
Location: India
GPA: 3.2
GMAT ToolKit User Premium Member
Re: If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers  [#permalink]

Show Tags

New post 27 Nov 2016, 08:29
Bunuel, need your insights -

((ab)^2+3ab-18)/(a-1)(a+2) = 0 --> (ab)^2+3ab-18 = 0 --> let ab be x --> x^2+3x-18=0 --> (x+6)(x-3) --> ab=3 or ab= -6 --> now a and b could be any of the factors of 3 or -6, that means all 3 statements could be true. Please let me know what I am missing, thank you.
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 9461
Premium Member
Re: If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers  [#permalink]

Show Tags

New post 19 Apr 2018, 21:58
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 ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers &nbs [#permalink] 19 Apr 2018, 21:58
Display posts from previous: Sort by

If ((ab)^2+3ab-18)((a-1)(a+2))=0 where a and b are integers

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


cron
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®.