4th order polynomials


by rlspin
Tags: order, polynomials
rlspin
rlspin is offline
#1
Nov28-10, 07:44 AM
P: 6
Hey everyone

Im doing control engineering and was wondering what methods i could use to find the roots of a 4th order polynomial?

For example:

(x^4) + (8x^3) + (7x^2) + 6x = 5

Could I seperate that into two brackets of quadratics or will i need to use a really long winded method?

Thanks in advance for any help
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Outlined
Outlined is offline
#2
Nov28-10, 10:38 AM
P: 124
'order'? You mean 'degree'! Well yes there is a solution for it but it is indeed long winded. You can try to find easy solutions by try. Else use Maple or Matlab.
Gib Z
Gib Z is offline
#3
Nov28-10, 11:23 AM
HW Helper
Gib Z's Avatar
P: 3,353
A formula exists for 4 degree polynomials analogously to the quadratic formula, but it is very long and complicated and coding it into a program would take too much time. Just numerically approximate all the roots.

rlspin
rlspin is offline
#4
Nov28-10, 11:46 AM
P: 6

4th order polynomials


Sorry, i do mean degree! Slipped up cos im working with a 4th order system.
I was worried id have to do it the long way.
I did use Matlab but wanted to see if I could work out the answer by hand.
Anywat, thanks for the help guys. I really appreciate it!
abypatel
abypatel is offline
#5
Jan30-12, 03:05 PM
P: 2
Quote Quote by rlspin View Post
Hey everyone

Im doing control engineering and was wondering what methods i could use to find the roots of a 4th order polynomial?

For example:

(x^4) + (8x^3) + (7x^2) + 6x = 5

Could I seperate that into two brackets of quadratics or will i need to use a really long winded method?

Thanks in advance for any help
also check this website

http://xrjunque.nom.es/precis/rootfinder.aspx


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