Solving fourth degree polynomial

1. May 1, 2007

j-lee00

Here it is

(x^4)-(3x^3)-(3x^2)+2 = 0

Two solutions are

x = 1 - i
x = 1 + i

How can i find the other solutions, (not graphically)

Thanks

2. May 1, 2007

General solution:
http://en.wikipedia.org/wiki/Quartic_equation

Numerical method:
http://en.wikipedia.org/wiki/Newton's_method

3. May 1, 2007

uart

Last edited by a moderator: May 2, 2017
4. May 1, 2007

good call.

5. May 2, 2007

HallsofIvy

Staff Emeritus
One serious problem the OP has is that 1-i and 1+ i are NOT roots of
x4-3x3-3x2+2= 0!

If x= 1- i then x4-3x3-3x2+2= 4+ 12i and if x= 1+ i then x4-3x3-3x2+2= 4- 12i, not 0.

6. May 2, 2007

uart

Oh yeah you're right. I just took his word for that and didn't check it.

My guess is that OP was given the two roots as part of the problem and has made a typo error in posting the equation.

7. May 2, 2007

j-lee00

yes sorry it was a typo but i got the method

thanks