Question

how to find the factors of a cubic polynomial​

Answer 1

Group the polynomial into two sections. Grouping the polynomial into two sections will let you attack each section individually.

[1]Say we're working with the polynomial x3 + 3x2 - 6x - 18 = 0. Let's group it into (x3 + 3x2) and (- 6x - 18)

2Find what's the common in each section.

Looking at (x3 + 3x2), we can see that x2 is common.

Looking at (- 6x - 18), we can see that -6 is common

3Factor the commonalities out of the two terms.

Factoring out x2 from the first section, we get x2(x + 3).

Factoring out -6 from the second section, you'll get -6(x + 3).

4

If each of the two terms contains the same factor, you can combine the factors together.[2]

This gives you (x + 3)(x2 - 6).

5

Find the solution by looking at the roots. If you have an x2 in your roots, remember that both negative and positive numbers fulfill that equation.[3]

The solutions are -3, √6 and -√6.