How can I get the roots of a polynomial?

Question

I have a polynomial,for example 3x⁴- 5x + 4.

Assume that I have an array A = { 3, 0, 0, -5, 4 } with the polynomial's coefficients.

How can I use the array A to find the roots of the polynomial?

Is there any function or library to download to do it?

[Note: Original question was about a quadratic: 3x²- 5x + 4.]

How can I get the roots of the polynomial and store them in a an array B?...

it is pretty easy algorithm - why not try to code it yourself? — Nogard, Oct 10 '13 at 12:46
Why did you edit the equation to be order 8? That will have a completely different solution technique. — Bathsheba, Oct 10 '13 at 15:08
Because that's what I want. I want to solve polynomial of all orders, not only quadratic... — Konstantinos_S, Oct 13 '13 at 07:17

Bathsheba · Answer 1 · 2013-10-10T12:51:00.607

2

For ax² + bx + c = 0 the solutions are

x = (-b + (b² - 4ac)^1/2) / 2a

and

x = (-b - (b² - 4ac)^1/2) / 2a

By the way, there are analytical solutions up to and including the 4^th degree.

edited Oct 10 '13 at 12:51

answered Oct 10 '13 at 12:47

Bathsheba

[Note that I answered this before OP edited the order of the polynomial to 8] – Bathsheba Oct 10 '13 at 15:06

score 0 · Answer 2 · answered Oct 10 '13 at 12:47

0

Mathematical Java libraries:

to list just a three of them. But you probably don't need a library to solve such a trivial equation.

answered Oct 10 '13 at 12:47

alex

score 0 · Answer 3 · answered Oct 10 '13 at 12:47

0

They have a sample code in the same link.

answered Oct 10 '13 at 12:47

Mkl Rjv

3 Answers3