# Factorising High order polynomials

1. Apr 18, 2015

### MMCS

Find roots of:

I need to set =0 then factorise. I know that this polynomial has coefficients of 1,2,4,8 and there is a rule to factorise this however, i dont know it.

Also, i believe a high order polynomial will be included in my exams. Are there any other "special" polynomials such as this which i should look out for to make factorizing easier as it has been suggested a polynomial such as this will come up....

Thanks

ADDED: i should add, this is not a homework question. I have the roots to be (s+2)(s^2+4)...but forgot to note how to arrive at this

Last edited: Apr 18, 2015
2. Apr 18, 2015

### Staff: Mentor

Your polynomial can't have (s + 2) has a factor, otherwise D(-2) would be zero, which it isn't. If the partial factorization you show is correct, then there's a typo in the polynomial whose image you attached. Otherwise, I don't know how you could get the factorization you show.

Also, when you post a question in the homework section, please use the homework template.

3. Apr 18, 2015

### SteamKing

Staff Emeritus
What happened to 10 and 6? These are coefficients as well.

If this is not a Homework question, then post it in the General Math forum.

4. Apr 18, 2015

### MMCS

Well its work. Im doing it at home. Your issue is pedantic.

5. Apr 18, 2015

### MMCS

Mark44....the fact that the roots are incorrect is irrelevant. My question is clearly asking how to treat a polynomial of this structure. Your response is therefore uselss

6. Apr 18, 2015

### SteamKing

Staff Emeritus
No, it's not.

By posting here in the Homework forums, which are intended to be used by students for their course work, there is only so much help which can be offered, according to the Rules of PF. No solutions of any kind can be given directly to the poster.

In the technical forums, these restrictions are relaxed, and this results in a very different kind of interaction between poster and those interested in replying.

7. Apr 18, 2015

### Staff: Mentor

How is this fact irrelevant? You post a problem, and say that you got a certain factorization, but that factorization is incorrect. Most people who post here would think that was relavant (and even valuable) information.

How about losing that attitude? You clearly came here for help, and to dismiss any help with such a snippy arrogant tone makes me less interested in providing that help, or even saying what I did to arrive at my answer. We are all unpaid volunteers here - we do it because we like to help out.

8. Apr 18, 2015

### MMCS

This is the 4th comment posted in this thread without any sort of constructive answer. Two "mentors" have jumped straight onto this thread with two seperate issues. It seems "mentors" on this site or more concerned with rules and regulations than helping people. Mark44 posted problem here is clear and concise, so to go out of your way to ask me to use the template without any sort of help with the actual problem is wasting both of our time.

9. Apr 18, 2015