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

It is currently 18 Dec 2018, 03:00

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 December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
  • Happy Christmas 20% Sale! Math Revolution All-In-One Products!

     December 20, 2018

     December 20, 2018

     10:00 PM PST

     11:00 PM PST

    This is the most inexpensive and attractive price in the market. Get the course now!
  • Key Strategies to Master GMAT SC

     December 22, 2018

     December 22, 2018

     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.

For which of the following functions f(x) is f(a + b) = f(a) ?

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

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51281
For which of the following functions f(x) is f(a + b) = f(a) ?  [#permalink]

Show Tags

New post 30 Jul 2018, 23:31
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

84% (00:58) correct 16% (01:06) wrong based on 55 sessions

HideShow timer Statistics

For which of the following functions f(x) is \(f(a + b) = f(a) + f(b)\)?


(A) \(f(x) = x^2\)

(B) \(f(x) = 5x\)

(C) \(f(x) = 2x + 1\)

(D) \(f(x) =\sqrt{x}\)

(E) \(f(x) = x - 2\)

_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

examPAL Representative
User avatar
G
Joined: 07 Dec 2017
Posts: 842
Re: For which of the following functions f(x) is f(a + b) = f(a) ?  [#permalink]

Show Tags

New post 31 Jul 2018, 00:32
Bunuel wrote:
For which of the following functions f(x) is \(f(a + b) = f(a) + f(b)\)?


(A) \(f(x) = x^2\)

(B) \(f(x) = 5x\)

(C) \(f(x) = 2x + 1\)

(D) \(f(x) =\sqrt{x}\)

(E) \(f(x) = x - 2\)


Instead of trying to work with the equations, we'll pick easy numbers to eliminate incorrect answers.
This is an Alternative approach.

Say a = 1 and b = 1, so a+b = 2.
Then (A) gives f(2) = 4 but f(1) + f(1) = 2. NO!
(B) gives f(2) = 10 and f(1)+f(1) = 10. Maybe let's check the others.
(C) gives f(2) = 5 but f(1) + f(1) = 6. NO!
(D) gives f(2) = \(\sqrt{2}\) while f(1)+f(1) = 2. NO
(E) gives f(2) = 0 and f(1) + f(1) = -2. NO

(B) must be our answer.
_________________

Image
Sign up for 7-day free trial
Image

Image

Claim your offer here.

Happy holidays!

Intern
Intern
avatar
B
Joined: 09 Jul 2018
Posts: 9
Re: For which of the following functions f(x) is f(a + b) = f(a) ?  [#permalink]

Show Tags

New post 31 Jul 2018, 16:43
I did not really understand what the question is asking, can someone explain the question?
Thank you in advance
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51281
Re: For which of the following functions f(x) is f(a + b) = f(a) ?  [#permalink]

Show Tags

New post 31 Jul 2018, 23:50
1
Sandy56 wrote:
I did not really understand what the question is asking, can someone explain the question?
Thank you in advance


I explained very similar question in detail HERE.

Also, check below topics:

13. Functions



For more check below:
ALL YOU NEED FOR QUANT ! ! !
Ultimate GMAT Quantitative Megathread

Hope it helps.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

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?
Extra-hard Quant Tests with Brilliant Analytics

Senior Manager
Senior Manager
avatar
P
Joined: 17 Mar 2014
Posts: 375
GMAT ToolKit User Premium Member Reviews Badge CAT Tests
For which of the following functions f(x) is f(a + b) = f(a) ?  [#permalink]

Show Tags

New post Updated on: 01 Aug 2018, 19:50
2
Sandy56 wrote:
I did not really understand what the question is asking, can someone explain the question?
Thank you in advance


Question asks which of below functions can behave like\(f(a+b)=f(a)+f(b)\).

Now what does\(f(a+b)\) mean ? It can be any function. when we reading question stem we don't know its value. We need to find out of available options.

Now what does\(f(a+b)=f(a)+f(b)\) mean ? it means, for example, f(5)=5 and f(6)=6 then f(5+6)= 5+6= f(5)+(6).

Now check available options one by one.

(A)\(f(x)=x^2\) => \(f(a)=a^2\) , \(f(b)=b^2\) and \(f(a+b)=(a+b)^2\)\(= a^2+2ab+b^2\) which is not equal to \(f(a)+(b)\)

(B)\(f(x)=5x\) =>\(f(a)=5a\), \(f(b)=5b\) and \(f(a+b)=5(a+b)= 5a+5b= f(a) +f(b)\) Whoohoo..here you go. This is the answer :)

(C) \(f(x)=2x+1\)

(D)\(f(x)=\sqrt{x}\)

(E) \(f(x)=x−2\)

Pls find similar question to practice: https://gmatclub.com/forum/for-which-of ... 24491.html

Originally posted by ammuseeru on 01 Aug 2018, 19:38.
Last edited by ammuseeru on 01 Aug 2018, 19:50, edited 1 time in total.
Senior Manager
Senior Manager
avatar
P
Joined: 17 Mar 2014
Posts: 375
GMAT ToolKit User Premium Member Reviews Badge CAT Tests
For which of the following functions f(x) is f(a + b) = f(a) ?  [#permalink]

Show Tags

New post 01 Aug 2018, 19:41
DavidTutorexamPAL wrote:
Bunuel wrote:
For which of the following functions f(x) is \(f(a + b) = f(a) + f(b)\)?


(A) \(f(x) = x^2\)

(B) \(f(x) = 5x\)

(C) \(f(x) = 2x + 1\)

(D) \(f(x) =\sqrt{x}\)

(E) \(f(x) = x - 2\)


Instead of trying to work with the equations, we'll pick easy numbers to eliminate incorrect answers.
This is an Alternative approach.

Say a = 1 and b = 1, so a+b = 2.
Then (A) gives f(2) = 4 but f(1) + f(1) = 2. NO!
(B) gives f(2) = 10 and f(1)+f(1) = 10. Maybe let's check the others.
(C) gives f(2) = 5 but f(1) + f(1) = 6. NO!
(D) gives f(2) = \(\sqrt{2}\) while f(1)+f(1) = 2. NO
(E) gives f(2) = 0 and f(1) + f(1) = -2. NO

(B) must be our answer.


In my opinion, it is very basic fundamental question. I don't know whether we really need number to put in and check. If student's basic math fundamentals are clear, Student should be able to solve it visually.
GMAT Club Bot
For which of the following functions f(x) is f(a + b) = f(a) ? &nbs [#permalink] 01 Aug 2018, 19:41
Display posts from previous: Sort by

For which of the following functions f(x) is f(a + b) = f(a) ?

  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®.