It is currently 27 Jun 2017, 07:05

### 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 n is an integer and f(n) = f(n 1) n, what is the value of

Author Message
TAGS:

### Hide Tags

Intern
Joined: 25 Apr 2011
Posts: 8
If n is an integer and f(n) = f(n 1) n, what is the value of [#permalink]

### Show Tags

15 Jun 2011, 15:30
1
KUDOS
2
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

64% (01:52) correct 36% (00:46) wrong based on 185 sessions

### HideShow timer Statistics

If n is an integer and f(n) = f(n – 1) – n, what is the value of f (4)?

(1) f(3) = 14

(2) f(6) = -1
[Reveal] Spoiler: OA
Manager
Joined: 08 Apr 2012
Posts: 128
Re: f(n) = f(n – 1) – n [#permalink]

### Show Tags

18 Dec 2012, 00:46
1
KUDOS
The equation says f(n) = f(n-1) - n
(1) states f(3)=14 and we need to find f(4)
so as per the equation, f(4) = f(4-1) -4
==> f(4)=f(3)-4
==> f(4)=14-4=10
So (1) is sufficient...Hope explanation for (2) is already clear. And this expalins the use of f(3)=14 as well.
_________________

Shouvik
http://www.Edvento.com

Current Student
Joined: 08 Jan 2009
Posts: 326
GMAT 1: 770 Q50 V46
Re: f(n) = f(n – 1) – n [#permalink]

### Show Tags

15 Jun 2011, 16:16
f(4) = f(3) - 4

1) Sufficient, slot straights into above equation.

2)
f(6) = -1 = f(5) - 6
f(5) = 5 = f(4) - 5
f(4) = 10

Sufficient

D.
Intern
Joined: 28 Jul 2011
Posts: 3
Concentration: Entrepreneurship, Organizational Behavior
GMAT Date: 10-18-2012
If n is an integer and f(n) = f(n – 1) – n, what is the [#permalink]

### Show Tags

02 Aug 2012, 15:58
If n is an integer and f(n) = f(n – 1) – n, what is the value of f (4)?

(1) f(3) = 14

(2) f(6) = -1

Last edited by Bunuel on 02 Aug 2012, 16:25, edited 1 time in total.
Moved to DS subforum and renamed the topic.
Math Expert
Joined: 02 Sep 2009
Posts: 39719
Re: If n is an integer and f(n) = f(n – 1) – n, what is the [#permalink]

### Show Tags

02 Aug 2012, 16:30
Expert's post
2
This post was
BOOKMARKED
If n is an integer and f(n) = f(n – 1) – n, what is the value of f (4)?

(1) f(3) = 14. Since f(n)=f(n-1)-n then: f(4)=f(3)-4 --> f(4)=14-4=10. Sufficient.

(2) f(6) = -1. The same way as above f(6)=f(5)-6 --> -1=f(5)-6 --> f(5)=5 --> f(5)=f(4)-5 --> 5=f(4)-5 --> f(4)=10. Sufficient.

_________________
Intern
Joined: 28 Apr 2012
Posts: 16
Re: f(n) = f(n – 1) – n [#permalink]

### Show Tags

17 Dec 2012, 21:55
pike wrote:
f(4) = f(3) - 4

1) Sufficient, slot straights into above equation.

2)
f(6) = -1 = f(5) - 6
f(5) = 5 = f(4) - 5
f(4) = 10

Sufficient

D.

I don't understand what you mean slot straights into above equation. When I simplify the f(3) I get -1 and for f(6) I also get -1. Is that why both are sufficient? I don't understand why Statement 1 the f(3)=14. What I supposed to do something else?
VP
Status: Been a long time guys...
Joined: 03 Feb 2011
Posts: 1381
Location: United States (NY)
Concentration: Finance, Marketing
GPA: 3.75
Re: f(n) = f(n – 1) – n [#permalink]

### Show Tags

17 Dec 2012, 22:25
dcastan2 wrote:
pike wrote:
f(4) = f(3) - 4

1) Sufficient, slot straights into above equation.

2)
f(6) = -1 = f(5) - 6
f(5) = 5 = f(4) - 5
f(4) = 10

Sufficient

D.

I don't understand what you mean slot straights into above equation. When I simplify the f(3) I get -1 and for f(6) I also get -1. Is that why both are sufficient? I don't understand why Statement 1 the f(3)=14. What I supposed to do something else?

Hii.
See the question gives us the relation: $$f(n)=f(n-1)-n$$ and the question asks the value of $$f(4)$$.

As per the above relation, if we expand $$f(4)$$, we get: $$f(4)=f(3)-4$$---------[a]

Now coming to the statements:
Statement 1 gives us direct $$f(3)$$. We just have to put in equation [a].
Statement 2 gives us $$f(6)=-1$$.
$$f(6)$$ can be expanded as $$f(5)$$-6. Moreover $$f(5)$$ can be expanded as $$f(4)-5$$. Put this value of $$f(5)$$ in the former one. It will become $$f(6)=f(4)-9$$, which will gives the value of $$f(4)$$ as 10.

Both are sufficient.
Hope that helps.
_________________
Intern
Joined: 28 Apr 2012
Posts: 16
Re: f(n) = f(n – 1) – n [#permalink]

### Show Tags

18 Dec 2012, 00:14
Marcab wrote:
dcastan2 wrote:
pike wrote:
f(4) = f(3) - 4

1) Sufficient, slot straights into above equation.

2)
f(6) = -1 = f(5) - 6
f(5) = 5 = f(4) - 5
f(4) = 10

Sufficient

D.

I don't understand what you mean slot straights into above equation. When I simplify the f(3) I get -1 and for f(6) I also get -1. Is that why both are sufficient? I don't understand why Statement 1 the f(3)=14. What I supposed to do something else?

Hii.
See the question gives us the relation: $$f(n)=f(n-1)-n$$ and the question asks the value of $$f(4)$$.

As per the above relation, if we expand $$f(4)$$, we get: $$f(4)=f(3)-4$$---------[a]

Now coming to the statements:
Statement 1 gives us direct $$f(3)$$. We just have to put in equation [a].
Statement 2 gives us $$f(6)=-1$$.
$$f(6)$$ can be expanded as $$f(5)$$-6. Moreover $$f(5)$$ can be expanded as $$f(4)-5$$. Put this value of $$f(5)$$ in the former one. It will become $$f(6)=f(4)-9$$, which will gives the value of $$f(4)$$ as 10.

Both are sufficient.
Hope that helps.

Yes, thank you! But we don't use the =14 anywhere? What's the purpose of it then?
VP
Status: Been a long time guys...
Joined: 03 Feb 2011
Posts: 1381
Location: United States (NY)
Concentration: Finance, Marketing
GPA: 3.75
Re: If n is an integer and f(n) = f(n 1) n, what is the value of [#permalink]

### Show Tags

18 Dec 2012, 00:41
In statement 1, put f(3)=14. You will get the answer as 10.
In DS, if you know that with the given information a particular question can be solved then rather than trying to find the exact answer, move to the next statement.
In the explanation, I did the same.

Hope that helps.
_________________
Math Expert
Joined: 02 Sep 2009
Posts: 39719
Re: f(n) = f(n – 1) – n [#permalink]

### Show Tags

18 Dec 2012, 03:13
dcastan2 wrote:
pike wrote:
f(4) = f(3) - 4

1) Sufficient, slot straights into above equation.

2)
f(6) = -1 = f(5) - 6
f(5) = 5 = f(4) - 5
f(4) = 10

Sufficient

D.

I don't understand what you mean slot straights into above equation. When I simplify the f(3) I get -1 and for f(6) I also get -1. Is that why both are sufficient? I don't understand why Statement 1 the f(3)=14. What I supposed to do something else?

Merging similar topics.

Solution is given here: if-n-is-an-integer-and-f-n-f-n-1-n-what-is-the-value-of-136745.html#p1109873
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16002
Re: If n is an integer and f(n) = f(n 1) n, what is the value of [#permalink]

### Show Tags

31 Jan 2014, 10:49
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 Club Legend
Joined: 09 Sep 2013
Posts: 16002
Re: If n is an integer and f(n) = f(n 1) n, what is the value of [#permalink]

### Show Tags

21 Mar 2016, 04:32
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 n is an integer and f(n) = f(n 1) n, what is the value of   [#permalink] 21 Mar 2016, 04:32
Similar topics Replies Last post
Similar
Topics:
If f(n)=4^n-3^n and n is a positive integer 2 08 Jun 2017, 15:22
6 If f(n) = xa^n, what is the value of f(5) ? 1 02 Apr 2017, 13:06
5 For all integers n, n* = n(n – 1). what is the value of x* 6 20 Oct 2016, 07:24
2 What is the value of the integer n? (1) N!= (N-1)!*N (2) 4 06 Jun 2011, 14:59
13 The function f(n) = the number of factors of n. If p and q 14 27 Dec 2016, 03:52
Display posts from previous: Sort by