Math Is Fun Forum

MKNB

Guest

Polynomial Factors

Finding factors of this equation  x^3  -12x   -16 =0

Jaspers

Member

Registered: 2019-05-24

Posts: 54

Re: Polynomial Factors

Hi MKNB.

Start by trying factors of the constant term: ±1, ±2, ±4, ±8, ±16. Substitute one of these, say 2, for x in the polynomial expression and see if you get zero:

We don’t get 0, so (x−2) is not a factor. Try x = −2 instead:

This time we do get zero, so (x+2) is a factor.

Once you have a factor, you can factorize the polynomial and find other factors.

Last edited by Jaspers (2019-05-26 04:53:50)

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Reason is like an open secret that can become known to anyone at any time; it is the quiet space into which everyone can enter through his own thought.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,619

Re: Polynomial Factors

hi MKNB

Welcome to the forum.

Jaspers has provided some good help.  If you want to know more about why this works have a look at this page:

https://www.mathsisfun.com/algebra/poly … actor.html

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob