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 Post subject: finding roots of the quartic eqautionPosted: Sat, 14 Jul 2007 13:23:29 UTC

Joined: Tue, 10 Jul 2007 16:46:13 UTC
Posts: 8
Location: lebanon
if in general,a quartic equation(4th degree equation) in the form ax^4+bx^3+cx^2+dx+e=0.

solve for x the following quartic equation:

12x^4+15x^3-30x^2+6x-3=0

find all the roots(real or complex)!

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Abed Zeidan/lebanon/saida.

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 Post subject: Posted: Sat, 14 Jul 2007 13:33:51 UTC
 Member of the 'S.O.S. Math' Hall of Fame

Joined: Thu, 1 Jan 2004 06:47:21 UTC
Posts: 2735
Location: Norman, Oklahoma
First of all, I'd divide both sides of the equation by 3. Then use Descartes' Rule of Signs. I can also tell that x=1 is a root of the equation so you should probably use the factor theorem and synthetic division to finish up.

Dave

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 Post subject: Posted: Sun, 29 Jul 2007 01:30:05 UTC
 Member of the 'S.O.S. Math' Hall of Fame

Joined: Tue, 6 Feb 2007 15:49:02 UTC
Posts: 2594
Where did this question come from? Are you happy to get the remaining real root and the two complex roots by just evaluating the "cubic formula"?

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