FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups 
 ProfileProfile   PreferencesPreferences   Log in to check your private messagesLog in to check your private messages   Log inLog in 
Forum index » Science and Technology » Math » Undergraduate
New Problem
Post new topic   Reply to topic Page 1 of 1 [15 Posts] View previous topic :: View next topic
Author Message
Michael Ward
science forum beginner


Joined: 30 Apr 2005
Posts: 22

PostPosted: Mon Jun 12, 2006 3:14 pm    Post subject: New Problem Reply with quote

How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I assume you have to factor it out first.
Back to top
Pubkeybreaker
science forum Guru


Joined: 24 Mar 2005
Posts: 333

PostPosted: Mon Jun 12, 2006 4:10 pm    Post subject: Re: New Problem Reply with quote

Lisa wrote:
Quote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I assume you have to factor it out first.

May I suggest that you show us what you have already done?
We are not here to do your homework for you.

Also, I thought this newsgroup was devoted to undergraduate level
math and not freshman high school level math???

I will give hints in socratic style:

(1) If one root is rational, what can you say about the other one?
(2) If m = a/b, for integers a and b, what can you say about a and
b
with respect to the coefficients of the polynomial?
(3) If the roots are not rational, then what method(s) are available to
solve it?
(4) What is the required condition on the discriminant for the roots to
be rational?
What is the value of the discriminant?
Back to top
cody.roux@gmail.com
science forum beginner


Joined: 30 Apr 2006
Posts: 34

PostPosted: Mon Jun 12, 2006 4:47 pm    Post subject: Re: New Problem Reply with quote

Lisa a écrit :

Quote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I assume you have to factor it out first.


1) open a textbook

2) read it

3) apply the appropriate result to your problem

Thanks! ;)

Cody
Back to top
Michael Ward
science forum beginner


Joined: 30 Apr 2005
Posts: 22

PostPosted: Mon Jun 12, 2006 5:20 pm    Post subject: Re: New Problem Reply with quote

nothing I do works..(2x-7)(x+1) (2x+7) (x-1) nothing works what am I doing wrong?
Back to top
Pubkeybreaker
science forum Guru


Joined: 24 Mar 2005
Posts: 333

PostPosted: Mon Jun 12, 2006 5:38 pm    Post subject: Re: New Problem Reply with quote

Lisa wrote:
Quote:
nothing I do works..(2x-7)(x+1) (2x+7) (x-1) nothing works what am I doing wrong?

Perhaps the fault lies in the assumption that it can be factored???????
Back to top
Paul1136
science forum beginner


Joined: 13 Nov 2005
Posts: 18

PostPosted: Mon Jun 12, 2006 6:02 pm    Post subject: Re: New Problem Reply with quote

Quote:

Lisa wrote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I
assume you have to factor it out first.

May I suggest that you show us what you have already
done?
We are not here to do your homework for you.

Also, I thought this newsgroup was devoted to
undergraduate level
math and not freshman high school level math???

Perhaps this is college pre-algebra or algebra at a University; hence, by definition undergraduate.


Quote:
I will give hints in socratic style:

(1) If one root is rational, what can you say about
the other one?
(2) If m = a/b, for integers a and b, what can
you say about a and
b
with respect to the coefficients of the polynomial?
(3) If the roots are not rational, then what
method(s) are available to
solve it?
(4) What is the required condition on the
discriminant for the roots to
be rational?
What is the value of the discriminant?
Back to top
Paul1136
science forum beginner


Joined: 13 Nov 2005
Posts: 18

PostPosted: Mon Jun 12, 2006 6:04 pm    Post subject: Re: New Problem Reply with quote

Quote:

Lisa a écrit :

How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I
assume you have to factor it out first.


1) open a textbook

2) read it

3) apply the appropriate result to your problem

Thanks! ;)

Cody



Sarcasm is really unnecessary.
Back to top
Paul1136
science forum beginner


Joined: 13 Nov 2005
Posts: 18

PostPosted: Mon Jun 12, 2006 6:06 pm    Post subject: Re: New Problem Reply with quote

Try completing the square or the quadratic formula. You can use both to double check your self.

If you try either and are still unsure... post what you have done and someone (hopefully less sarcastic then previous posts) will show you your mistakes.

Paul
Back to top
Dana DeLouis
science forum beginner


Joined: 06 Mar 2006
Posts: 37

PostPosted: Mon Jun 12, 2006 11:45 pm    Post subject: Re: New Problem Reply with quote

Quote:
The question is asking me to find the roots

I think you are looking for the following...
http://mathworld.wolfram.com/QuadraticFormula.html

Quote:
...I assume you have to factor it out first?

Some can be factored, but this one in particular doesn't seem to factor into
anything useful...as far as I can tell.
Good luck...
--
HTH. :>)

Dana

"Lisa" <mikeward1980@yahoo.com> wrote in message
news:20717893.1150125300808.JavaMail.jakarta@nitrogen.mathforum.org...
Quote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I assume you have to
factor it out first.
Back to top
Bob111
science forum Guru Wannabe


Joined: 13 Jan 2006
Posts: 115

PostPosted: Tue Jun 13, 2006 1:25 am    Post subject: Re: New Problem Reply with quote

On Mon, 12 Jun 2006 11:14:30 EDT, Lisa <mikeward1980@yahoo.com> wrote:

Quote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I assume you have to factor it out first.


If you have a quadratic equation and aren't sure how to approach it,
the best general way is to use the quadratic formula. If you can
easily find factors, fine, but spending much time looking for them is
not so good. Just go directly to the general method, the quadratic
equation.

bob
Back to top
Paul1136
science forum beginner


Joined: 13 Nov 2005
Posts: 18

PostPosted: Tue Jun 13, 2006 2:56 am    Post subject: Re: New Problem Reply with quote

Quote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I
assume you have to factor it out first.


I'm getting tired of see everyone post ... so here it is.

Completing the square:

2x^2 - x - 7 = 0

Add 7 to both sides.

=> 2x^2 - x = 7

Multiply through by 1/2.

=> x^2 - (1/2)x = (7/2)

Complete the square by taking half the coefficient of x, square it and add it to both sides. We have,

((-1/2)/2)^2 = 1/16 and so

=> x^2 - (1/2)x + (1/16) = (7/2) + (1/16)

Simplify.

=> (x - (1/4))^2 = (57/16)

Square root both sides.

=> x - (1/4) = +- (sqrt(57)/4)

Add 1/4 to both side.

=> x = (1 +- sqrt(57))/4

The end.

Use quadratic formula to check my work.
Back to top
David C. Ullrich
science forum Guru


Joined: 28 Apr 2005
Posts: 2250

PostPosted: Tue Jun 13, 2006 9:05 am    Post subject: Re: New Problem Reply with quote

On Mon, 12 Jun 2006 11:14:30 EDT, Lisa <mikeward1980@yahoo.com> wrote:

Quote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I assume you have to factor it out first.

Factoring is not the only way to find the roots... once you find the
roots you'll see why you couldn't factor it.


************************

David C. Ullrich
Back to top
David C. Ullrich
science forum Guru


Joined: 28 Apr 2005
Posts: 2250

PostPosted: Tue Jun 13, 2006 9:09 am    Post subject: Re: New Problem Reply with quote

On Mon, 12 Jun 2006 14:04:16 EDT, Paul <kryptos@verizon.net> wrote:

Quote:

Lisa a écrit :

How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I
assume you have to factor it out first.


1) open a textbook

2) read it

3) apply the appropriate result to your problem

Thanks! ;)

Cody



Sarcasm is really unnecessary.

What sarcasm? What he wrote was excellent advice!

The OP has clearly just not learned one or two important
techniques that were covered in class - explaining to her
that she shouldn't expect to succeed in a math class if
she hasn't been bothering to learn the material is a
much more valuable bit of information than the solution
to this particular problem...

************************

David C. Ullrich
Back to top
denver
science forum beginner


Joined: 28 Apr 2006
Posts: 10

PostPosted: Tue Jun 13, 2006 10:06 am    Post subject: Re: New Problem Reply with quote

Lisa wrote:
Quote:
How do you factor 2m^2 - m - 7 = 0

The question is asking me to find the roots, and I assume you have to factor it out first.

I DONT SEE WHAT CAN BE THAT DIFFICULT IN THIS PROBLEM BECAUSE IT HAS
BEEN KNOW THAT IF IT DIFFICULT TO FACTOR AN EQUATION, YOU MUST USE THE
GENERAL FORMULAR( QUADRATIC FORMULAR) ax^2+bx+c, that all!!
Back to top
tommy1729
science forum beginner


Joined: 23 Feb 2006
Posts: 33

PostPosted: Wed Jun 14, 2006 11:53 pm    Post subject: Re: New Problem Reply with quote

yeah sounds more like old classic low level problem to me :p
Back to top
Google

Back to top
Display posts from previous:   
Post new topic   Reply to topic Page 1 of 1 [15 Posts] View previous topic :: View next topic
The time now is Mon Jun 20, 2011 1:40 am | All times are GMT
Forum index » Science and Technology » Math » Undergraduate
Jump to:  

Similar Topics
Topic Author Forum Replies Last Post
No new posts help on problem brb003 Math 0 Mon Aug 28, 2006 3:31 am
No new posts fraction problem mikerule Research 0 Thu Aug 24, 2006 5:10 am
No new posts Mod computer problem William Elliot Math 4 Fri Jul 21, 2006 12:07 pm
No new posts Divine apparitions in the tethered goat problem? jpalmour@gmail.com Math 6 Thu Jul 20, 2006 8:26 pm
No new posts possible to use Generalized Method of Moments for this pr... comtech Math 1 Thu Jul 20, 2006 12:49 am

Copyright © 2004-2005 DeniX Solutions SRL
Other DeniX Solutions sites: Electronics forum |  Medicine forum |  Unix/Linux blog |  Unix/Linux documentation |  Unix/Linux forums  |  send newsletters
 


Powered by phpBB © 2001, 2005 phpBB Group
[ Time: 0.5473s ][ Queries: 16 (0.4765s) ][ GZIP on - Debug on ]