 It is currently 25 Mar 2019, 00:18 ### 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

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. # For all integers a and b, a # b = –|a + b|  Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
Moderator  Joined: 18 Apr 2015
Posts: 5898
Followers: 96

Kudos [?]: 1156 , given: 5481

For all integers a and b, a # b = –|a + b| [#permalink]
Expert's post 00:00

Question Stats: 80% (00:31) correct 19% (01:00) wrong based on 61 sessions

For all integers a and b, a # b = –|a + b|

 Quantity A Quantity B (–10) # 7 7 – 10

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
[Reveal] Spoiler: OA

_________________ GRE Instructor Joined: 10 Apr 2015
Posts: 1543
Followers: 56

Kudos [?]: 1468  , given: 8

Re: For all integers a and b, a # b = –|a + b| [#permalink]
1
KUDOS
Expert's post
Carcass wrote:

For all integers a and b, a # b = –|a + b|

 Quantity A Quantity B (–10) # 7 7 – 10

A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.

a # b = –|a + b|
So, (–10) # 7 = –|(-10) + 7|
= -|-3|
= -(3)
= -3

So, we get:
Quantity A: -3
Quantity B: 7 - 10

[Reveal] Spoiler:
C

RELATED VIDEO

_________________

Brent Hanneson – Creator of greenlighttestprep.com Sign up for our free GRE Question of the Day emails Intern Joined: 08 Dec 2017
Posts: 40
Followers: 1

Kudos [?]: 39  , given: 70

Re: For all integers a and b, a # b = –|a + b| [#permalink]
1
KUDOS
Given that, all integers a and b, a # b = –|a + b|
Q.A (–10) # 7 = - |-10+7| = - |-3| = -3
Q.B 7-10 = -3

So the answer is C
Intern Joined: 11 Jan 2018
Posts: 44
Followers: 0

Kudos [?]: 33 , given: 7

Re: For all integers a and b, a # b = –|a + b| [#permalink]
Answer is clearly C
It's an easy question.
_________________

Persistence >>>>>>> Success

Don't say thanks, just give KUDOS.
1 kudos = 1000 Thanks

Intern Joined: 17 Feb 2018
Posts: 9
Followers: 0

Kudos [?]: 2 , given: 2

Re: For all integers a and b, a # b = –|a + b| [#permalink]
GREMasterBlaster wrote:
Answer is clearly C
It's an easy question.

easy to get tripped up, since the intergers used are A and B, and the option choices are A and B
Intern Joined: 12 Aug 2018
Posts: 9
Followers: 0

Kudos [?]: 3 , given: 3

Re: For all integers a and b, a # b = –|a + b| [#permalink]
Since |a|=-a when a<0, Shouldn't we also test for -(-|-10+7|) which gives us 3. Hence it could be -3 or 3 isn't it? Thanks for the clarification.
Moderator  Joined: 18 Apr 2015
Posts: 5898
Followers: 96

Kudos [?]: 1156 , given: 5481

Re: For all integers a and b, a # b = –|a + b| [#permalink]
Expert's post
in a#b you just need to substitute.

a = -10 and b = 7

QA - |a+b|= - |-3|= - |3| (insde the absolute value) = -3

QB is -3

_________________
Intern Joined: 02 Jan 2019
Posts: 13
Followers: 0

Kudos [?]: 2 , given: 9

Re: For all integers a and b, a # b = –|a + b| [#permalink]
I agree with Runnyboy44's doubts about the answer. How are we supposed to know that we do not have to consider the case - -(|-3|) = +3 in this case?

This doubt could be corroborated by looking at exercises where the function is defined as a # b = (+)|a + b|. Then I would seperate between case 1:

a # b = (+)|a + b|

and case 2: a # b = (-)|a + b|

.

how are we supposed to that we should limit our answer strategy to plugging in.
Supreme Moderator
Joined: 01 Nov 2017
Posts: 370
Followers: 5

Kudos [?]: 107 , given: 4

Re: For all integers a and b, a # b = –|a + b| [#permalink]
Expert's post
Zamala wrote:
I agree with Runnyboy44's doubts about the answer. How are we supposed to know that we do not have to consider the case - -(|-3|) = +3 in this case?

This doubt could be corroborated by looking at exercises where the function is defined as a # b = (+)|a + b|. Then I would seperate between case 1:

a # b = (+)|a + b|

and case 2: a # b = (-)|a + b|

.

how are we supposed to that we should limit our answer strategy to plugging in.

Hi..

we have to just read the information given in the question while we solve a question.
The question gives us a function a # b = (-)|a + b|...
Now you have to find (-10)#7, this means a=-10 and b=7, so substitute in the function to get (-10)#7=-|-10+7|=-3

|a|=-a when a<0.. But this is true when you do not know the value of a. Here you know what a and b stands for..

Even here a+b=-10+7=-3<0 so |a+b|=-(a+b) when (a+b)<0 thus |-10+7|=-(-10+7)=-(-3)=3..
But we are looking for -(|a+b|), which will be equal to -(3)
_________________

Some useful Theory.
1. Arithmetic and Geometric progressions : https://greprepclub.com/forum/progressions-arithmetic-geometric-and-harmonic-11574.html#p27048
2. Effect of Arithmetic Operations on fraction : https://greprepclub.com/forum/effects-of-arithmetic-operations-on-fractions-11573.html?sid=d570445335a783891cd4d48a17db9825
3. Remainders : https://greprepclub.com/forum/remainders-what-you-should-know-11524.html
4. Number properties : https://greprepclub.com/forum/number-property-all-you-require-11518.html
5. Absolute Modulus and Inequalities : https://greprepclub.com/forum/absolute-modulus-a-better-understanding-11281.html Re: For all integers a and b, a # b = –|a + b|   [#permalink] 28 Jan 2019, 18:59
Display posts from previous: Sort by

# For all integers a and b, a # b = –|a + b|  Question banks Downloads My Bookmarks Reviews Important topics  Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.