# Factoring question

• Jan 31st 2010, 02:05 PM
james121515
Factoring question
Hi,

What is the best method to go about factoring this $x^6+6x^4+10x^2+8$? Can this be done by grouping? I tried to do rational root tests but it appears as though it does not have any rational roots.

James
• Jan 31st 2010, 02:13 PM
pickslides
Quote:

Originally Posted by james121515
Hi,

What is the best method to go about factoring this $x^6+6x^4+10x^2+8$? Can this be done by grouping? I tried to do rational root tests but it appears as though it does not have any rational roots.

James

Might be helpful to say $a = x^2$ making the whole thing cubic instead.
• Jan 31st 2010, 02:16 PM
skeeter
Quote:

Originally Posted by james121515
Hi,

What is the best method to go about factoring this $x^6+6x^4+10x^2+8$? Can this be done by grouping? I tried to do rational root tests but it appears as though it does not have any rational roots.

James

$y = x^6+6x^4+10x^2+8 > 0$ for all $x$ ... no real roots.
• Jan 31st 2010, 02:17 PM
Henryt999
Well
Thats an expression you have no = sign anywhere.
Also it doesn´t have any x intercepts so it doesn´t factor.
• Jan 31st 2010, 02:25 PM
james121515
It factors to $(x^2+2)^3$. I'm curious as to what method you use to do it.
• Jan 31st 2010, 02:33 PM
pickslides
Quote:

Originally Posted by james121515
It factors to $(x^2+2)^3$. I'm curious as to what method you use to do it.

$x^6+6x^4+10x^2+8$

make $a = x^2$ now

$a^3+6a^2+10a+8$

Then employee the factor theorem checking positive and negative factors of 8.

Spoiler:
$a = -2$