Register to reply 
Roots of a 4th degree polynomial 
Share this thread: 
#1
Nov1206, 10:00 PM

P: 4

Hi eveveryone I was just hoping for some quick help on frustrating physics related math problem. I won't go into detail on the actual problem becasue i know i found the correct polynomial but i was wondering if there was any easy way to find the roots to this polynomial:
3x^4960x^3+91500x^26272000x+501760000=f(x) *sorry i haven't figured out how to use latex or w/e it's called* rational roots seems rather arduous with the numbers involved. Any suggestions?(I know there is only one answer about 125.98 i think but i was wondering if there was a way to find an exact answer algebraically or with calculus or something) 


#2
Nov1206, 10:33 PM

HW Helper
P: 2,277

Apart from using Ruffini's method (rational roots) or Newton's method, both which will require time to yield answers, maybe since this isn't a mathematical problem you can use Mathematica, Matlab, etc... for your solutions.
Also you could have tried Descartes' sign rule, but that wouldn't have helped much anyway. 


#3
Nov1206, 10:45 PM

Emeritus
Sci Advisor
PF Gold
P: 16,091




#4
Nov1206, 11:18 PM

P: 4

Roots of a 4th degree polynomial
I don't think that the roots are rational now that i've looked at a it or a while,
Cyclovenom if you could explain any of those methods i might try them. 


#5
Nov1206, 11:57 PM

HW Helper
P: 2,277

Newton's Method http://www.ugrad.math.ubc.ca/coursed...ox/newton.html http://www.sosmath.com/calculus/diff/der07/der07.html Ruffini's Method http://en.wikipedia.org/wiki/Ruffini's_rule 


#6
Nov1306, 12:08 AM

P: 4

wow, the newton method is PERFECT for what I wanted, plus it will also give my teacher a huge laugh (inside joke about approximations)
Thank you SOO much :) 


Register to reply 
Related Discussions  
Show a polynomial of degree n has at most n distint roots  Linear & Abstract Algebra  2  
Roots of polynomial  General Math  12  
Roots of polynomial  Linear & Abstract Algebra  3  
Roots of a polynomial of degree 4  Calculus & Beyond Homework  2  
Roots of a polynomial  Introductory Physics Homework  6 