GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 30 Mar 2020, 15:21 ### 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.  # (x + 7) is a factor in x^2 - mx - 56. What is the value of m

Author Message
TAGS:

### Hide Tags

Director  Status: Final Lap Up!!!
Affiliations: NYK Line
Joined: 21 Sep 2012
Posts: 821
Location: India
GMAT 1: 410 Q35 V11
GMAT 2: 530 Q44 V20
GMAT 3: 630 Q45 V31
GPA: 3.84
WE: Engineering (Transportation)
(x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

2
5 00:00

Difficulty:   15% (low)

Question Stats: 71% (00:53) correct 29% (01:17) wrong based on 213 sessions

### HideShow timer Statistics

(x + 7) is a factor in x^2 - mx - 56. What is the value of m?

A. 1
B. 8
C. 14
D. 15
E. 16

Originally posted by Archit143 on 05 Dec 2012, 07:00.
Last edited by Bunuel on 05 Dec 2012, 07:03, edited 1 time in total.
Edited the question.
Director  Status: Been a long time guys...
Joined: 03 Feb 2011
Posts: 967
Location: United States (NY)
Concentration: Finance, Marketing
GPA: 3.75
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

1
2
Given the fact that $$(x+7)$$ is the factor of the equation,
so it claerly means that one value of x=-7; the other we don't know and we don't have to.

The equation can be written in factor form as:
$$(x+7)*(x+a)$$ where a is the other value of x.

On putting the value of x=-7 in the equation,
$$x^2-mx-56=0$$

we get:

$$49+7m-56=0$$

$$-7=-7m$$
$$m=1$$

+1 A.
_________________
Director  Status: Final Lap Up!!!
Affiliations: NYK Line
Joined: 21 Sep 2012
Posts: 821
Location: India
GMAT 1: 410 Q35 V11
GMAT 2: 530 Q44 V20
GMAT 3: 630 Q45 V31
GPA: 3.84
WE: Engineering (Transportation)
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

thanks marcab just wanted to be sure of my approach
Senior Manager  Status: Math is psycho-logical
Joined: 07 Apr 2014
Posts: 395
Location: Netherlands
GMAT Date: 02-11-2015
WE: Psychology and Counseling (Other)
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

I solved the second degree equation and found it like this:

x^2 - mx - 56 = 0
(x-8)(x+7) = 0
x=8 or x= -7

Substituting both values for x in the equation we find:
x^2 - mx - 56
=> (-7)^2 - m(-7) - 56
=> 49 - 56 + 7m
=> -49 + 56 = 7m
=> 7 = 7m
=> m = 1

And with 8, using a similar process we end up with:
64-56=8m
8=8m
m=1

Ao, ANS A
Manager  B
Joined: 16 Jan 2013
Posts: 70
GMAT 1: 490 Q41 V18 GMAT 2: 610 Q45 V28 GPA: 2.75
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

l got the same answer. lt's not stated in the question stem that x^2 - mx - 56 = 0. Based on what information do we know (x^2 - mx - 56) equals to zero? Could someone please clarify? Regards,
Curious mind.
_________________
Math Expert V
Joined: 02 Aug 2009
Posts: 8296
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

1
l got the same answer. lt's not stated in the question stem that x^2 - mx - 56 = 0. Based on what information do we know (x^2 - mx - 56) equals to zero? Could someone please clarify? Regards,
Curious mind.

Hi,

x^2-mx-56 can be any value depending on value of x.....
this equation is that of PARABOLA, so you will get a parabola when you draw a graph of it...

Just remember for GMAT that
but when we factor or find roots, we work for ONLY those values of x at which the equation gives us a 0 value..

That is why when we are factoring the equation here we take the equation to be equal to 0...

so If I tell you the speed of something is dependent on x^2-15x+56
and then ask you speed at say 9h second, substitute x as 9 and find the answer..
But if I ask you at what values will the speed be 0, put the equation as 0 and find values of x..
_________________
Manager  Joined: 18 Jan 2010
Posts: 237
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

Archit143 wrote:
(x + 7) is a factor in x^2 - mx - 56. What is the value of m?

A. 1
B. 8
C. 14
D. 15
E. 16

If (x+7) is a factor of expression x^2 - mx - 56, then if we substitute x = -7, in the given expression, the value of expression will be zero.

So, (-7)^2 - (m)(-7) - 56 = 0

49+7m-56 = 0

7m-7=0

m=1

Target Test Prep Representative G
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2801
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

Archit143 wrote:
(x + 7) is a factor in x^2 - mx - 56. What is the value of m?

A. 1
B. 8
C. 14
D. 15
E. 16

Since (x + 7) is a factor of x^2 - mx - 56, we know that x = -7 will satisfy the equation x^2 - mx - 56 = 0; therefore, we can substitute -7 for x and we have:

(-7)^2 - 7m - 56 = 0

49 - 7m = 56

-7m = -7

m = 1

_________________

# Jeffrey Miller

Jeff@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.

VP  V
Status: Learning
Joined: 20 Dec 2015
Posts: 1090
Location: India
Concentration: Operations, Marketing
GMAT 1: 670 Q48 V36
GRE 1: Q157 V157
GPA: 3.4
WE: Engineering (Manufacturing)
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

Imo A
Substitute the value x=-7
We get m=1

Sent from my ONE E1003 using GMAT Club Forum mobile app
Non-Human User Joined: 09 Sep 2013
Posts: 14449
Re: (x + 7) is a factor in x^2 - mx - 56. What is the value of m  [#permalink]

### Show Tags

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: (x + 7) is a factor in x^2 - mx - 56. What is the value of m   [#permalink] 03 Feb 2019, 20:51
Display posts from previous: Sort by

# (x + 7) is a factor in x^2 - mx - 56. What is the value of m  