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

 It is currently 23 May 2019, 22:28 ### 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. ### Request Expert Reply # If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =

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

### Hide Tags

Math Expert V
Joined: 02 Sep 2009
Posts: 55276
If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =  [#permalink]

### Show Tags 00:00

Difficulty:   45% (medium)

Question Stats: 62% (01:48) correct 38% (01:51) wrong based on 68 sessions

### HideShow timer Statistics

If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =

A. 0.5
B. 1
C. 3
D. 4
E. 6

_________________
CEO  D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2931
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =  [#permalink]

### Show Tags

1
Bunuel wrote:
If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =

A. 0.5
B. 1
C. 3
D. 4
E. 6

f(x) = 5 - 2x

f(3k) = 5-2(3k) = 5 - 6k

f(k+1) = 5-2(k+1) = 3 - 2k

f(3k) = f(k + 1)

i.e 5 - 6k = 3 - 2k

i.e. k = 0.5

i.e. f(k) = 5-2(0.5) = 4

Answer: Option D
_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION

Originally posted by GMATinsight on 23 Oct 2018, 22:09.
Last edited by GMATinsight on 23 Oct 2018, 22:39, edited 1 time in total.
Senior Manager  P
Joined: 13 Jan 2018
Posts: 326
Location: India
Concentration: Operations, General Management
GMAT 1: 580 Q47 V23 GMAT 2: 640 Q49 V27 GPA: 4
WE: Consulting (Consulting)
Re: If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =  [#permalink]

### Show Tags

Hi GMATinsight

The question is asking for f(k) not for k value.

K is $$\frac{1}{2}$$

So f(k) = 5-2($$\frac{1}{2}$$)

f(k) = 5-1 => 4

OPTION : D
_________________
____________________________
Regards,

Chaitanya

+1 Kudos

if you like my explanation!!!
Intern  B
Joined: 23 Oct 2018
Posts: 6
GMAT 1: 760 Q50 V42 If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =  [#permalink]

### Show Tags

1
The first thing to notice here is that we’re solving for $$f(k)$$, not $$k$$ itself. Make a note, circle it, underline it, do whatever you need to do to remind yourself what you’re actually solving for!

The next step is to see that we’re given $$f(3k) = f(k+1)$$. Let’s simplify by “getting rid” of these functions and plug in the values provided, which are $$3k$$ and $$k+1$$.

Given that $$f(x) = 5 - 2x$$, we get:

$$5-2(3k)$$ = $$5-2(k+1)$$

Solving, we get:

$$5-6k = 5-2k-2$$

$$-4k = -2$$

$$k = 1/2$$

Choice A is a trap! Remember that we’re solving for $$f(k)$$, not $$k$$. Let’s plug our $$k$$ value back into $$f(x)$$.

$$f(1/2) = 5 - 2(1/2) = 4$$

Answer D.
e-GMAT Representative D
Joined: 04 Jan 2015
Posts: 2873
Re: If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =  [#permalink]

### Show Tags

Solution

Given:
• f(x) = 5 – 2x
• f(3k) = f(k + 1)

To find:
• The value of f(k)

Approach and Working:
• f(3k) = 5 – 2(3k) = 5 – 6k
• f(k + 1) = 5 – 2(k + 1) = 3 – 2k
• We are given, f(3k) = f(k + 1)
o Implies, 5 – 6k = 3 – 2k
o Thus, $$k = \frac{1}{2}$$
• Therefore, f(k) = $$5 – 2(\frac{1}{2}) = 4$$

Hence, the correct answer is Option D.

Answer: D

_________________
Intern  Joined: 24 Oct 2018
Posts: 10
Re: If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =  [#permalink]

### Show Tags

K is 1212

So f(k) = 5-2(1212)

f(k) = 5-1 => 4

D
Target Test Prep Representative D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 6228
Location: United States (CA)
Re: If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =  [#permalink]

### Show Tags

Bunuel wrote:
If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =

A. 0.5
B. 1
C. 3
D. 4
E. 6

We are given that f(x) = 5 - 2x. So f(3k) = 5 - 2(3k) = 5 - 6k and f(k + 1) = 5 - 2(k + 1) = 3 - 2k. Since f(3k) = f(k + 1), we equate the two expressions, and thus:

5 - 6k = 3 - 2k

2 = 4k

0.5 = k

Therefore, f(k) = f(0.5) = 5 - 2(0.5) = 4.

Answer: D
_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button. Re: If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =   [#permalink] 28 Oct 2018, 18:20
Display posts from previous: Sort by

# If f(x) = 5 - 2x and f(3k) = f(k + 1), then f(k) =

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

#### MBA Resources  