# Grouping polynomials to show a common factor

• Jan 17th 2008, 06:23 PM
PandaPanda
Grouping polynomials to show a common factor
y^3 + y^2 - 3y - 3

I've just gotten transferred to this alien math class in my new school. I just need someone to help me factor this equation so I can get a feeling of what I should do.

So far I've gotten as far as: y(y^2+y-3)-3
I don't think I'm going the right direction, but if I am, what next? Please help ;_;
• Jan 17th 2008, 06:26 PM
ThePerfectHacker
Quote:

Originally Posted by PandaPanda
y^3 + y^2 - 3y - 3

I've just gotten transferred to this alien math class in my new school. I just need someone to help me factor this equation so I can get a feeling of what I should do.

So far I've gotten as far as: y(y^2+y-3)-3
I don't think I'm going the right direction, but if I am, what next? Please help ;_;

$y^3 + y^2 - 3y - 3 = y^2(y+1) - 3(y+1) = (y+1)(y^2 - 3)$
• Jan 17th 2008, 06:48 PM
PandaPanda
Thanks so much, that was very helpful.
I just need help with one more problem on making something a perfect square trinomial to factor a difference of squares.

a^4 + 4b^4

I don't know the first step.
• Jan 17th 2008, 06:51 PM
Jhevon
Quote:

Originally Posted by PandaPanda
Thanks so much, that was very helpful.
I just need help with one more problem on making something a perfect square trinomial to factor a difference of squares.

a^4 + 4b^4

I don't know the first step.

you don't have a difference of squares here. and should that 4 be in front of the b?
• Jan 17th 2008, 06:53 PM
ThePerfectHacker
Quote:

Originally Posted by PandaPanda
Thanks so much, that was very helpful.
I just need help with one more problem on making something a perfect square trinomial to factor a difference of squares.

a^4 + 4b^4

I don't know the first step.

$a^4 + 4b^4 = (a^2)^2 + (2b^2)^2$
$(a^2)^2 + 2(a^2)(2b^2)+(2b^2)^2 - 2(a^2)(2b^2)$
$(a^2+2b^2)^2 - (2ab)^2 = (a^2 + 2b^2 + 2ab)(a^2+2b^2 - 2ab)$