If f(x) = k(x - k) and k is a constant, what is the value : GMAT Problem Solving (PS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 18 Jan 2017, 03:08

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If f(x) = k(x - k) and k is a constant, what is the value

Author Message
TAGS:

### Hide Tags

Director
Status: 1,750 Q's attempted and counting
Affiliations: University of Florida
Joined: 09 Jul 2013
Posts: 513
Location: United States (FL)
Schools: UFL (A)
GMAT 1: 600 Q45 V29
GMAT 2: 590 Q35 V35
GMAT 3: 570 Q42 V28
GMAT 4: 610 Q44 V30
GPA: 3.45
WE: Accounting (Accounting)
Followers: 26

Kudos [?]: 746 [1] , given: 630

If f(x) = k(x - k) and k is a constant, what is the value [#permalink]

### Show Tags

24 Oct 2013, 09:26
1
KUDOS
1
This post was
BOOKMARKED
00:00

Difficulty:

5% (low)

Question Stats:

80% (01:40) correct 20% (00:45) wrong based on 99 sessions

### HideShow timer Statistics

If f(x) = k(x - k) and k is a constant, what is the value of f(4) - f(3), in terms of k?

(A) 1
(B) k
(C) 7k - 1
(D) k^2 + k
(E) k^2 - k

GH-04.12.13 | OE to follow
[Reveal] Spoiler: OA
Moderator
Status: It always seems impossible until it's done!!
Joined: 29 Aug 2012
Posts: 699
Location: India
GMAT 1: 680 Q49 V34
Followers: 60

Kudos [?]: 1024 [1] , given: 226

Re: If f(x) = k(x - k) and k is a constant, what is the value [#permalink]

### Show Tags

24 Oct 2013, 09:38
1
KUDOS
avohden wrote:
If f(x) = k(x - k) and k is a constant, what is the value of f(4) - f(3), in terms of k?

(A) 1
(B) k
(C) 7k - 1
(D) k^2 + k
(E) k^2 - k

GH-04.12.13 | OE to follow

f(x)= k(x-k).
f(4)= k(4-k).
f(3)=k(3-k).

f(4)-f(3)= [k(4-k)-k(3-k)].. taking the common k out.

= k[4-k-3+k]---- +k and -k cancelled out.
=k[1]

_________________
Director
Status: 1,750 Q's attempted and counting
Affiliations: University of Florida
Joined: 09 Jul 2013
Posts: 513
Location: United States (FL)
Schools: UFL (A)
GMAT 1: 600 Q45 V29
GMAT 2: 590 Q35 V35
GMAT 3: 570 Q42 V28
GMAT 4: 610 Q44 V30
GPA: 3.45
WE: Accounting (Accounting)
Followers: 26

Kudos [?]: 746 [0], given: 630

Re: If f(x) = k(x - k) and k is a constant, what is the value [#permalink]

### Show Tags

27 Oct 2013, 09:40
Official Explanation

First, distribute f(x). k(x - k) = kx - k^2. Now evaluate f(4) and f(3):

f(4) = k(4) - k^2 = 4k - k^2

f(3) = 3k - k^2

Now subtract: (4k - k^2) - (3k - k^2) ---> = 4k - k^2 - 3k + k^2 ---> = 4k - 3k = k, choice (B).
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13435
Followers: 575

Kudos [?]: 163 [0], given: 0

Re: If f(x) = k(x - k) and k is a constant, what is the value [#permalink]

### Show Tags

14 Nov 2014, 21:48
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.
_________________
Re: If f(x) = k(x - k) and k is a constant, what is the value   [#permalink] 14 Nov 2014, 21:48
Similar topics Replies Last post
Similar
Topics:
1 (3x + 2) (2x - 5) = ax² + kx + n . What is the value of a - n + k ? 2 12 May 2016, 00:45
8 In the equation x^2+kx+1=0, x is a variable and k is a constant 3 10 Aug 2015, 16:53
4 If f(x) = 12 - x^2/2 and f(2k) = 2k, what is one possible value for k? 5 19 Mar 2015, 05:26
15 Given f(x) = x/(x + 1), for what value k does f(f(k)) = 2/3 ? 12 19 Jan 2015, 04:16
32 For what values of k will the pair of equations 3x + 4y = 12 and kx + 9 13 Apr 2007, 00:22
Display posts from previous: Sort by