Factor this math problem for 10 points?

Question

Factor as many as possible i dont know how to do these things at all please step by step so i can learn it or a link would be appreciated i need to learn these things!!

x^4 - y^4

6x^2 - xy - 12y^2

12(x+y)^2 + 8(x+y) - 15

Answer 1

1). x^4-y^4
=difference of squares, (x^2-y^2)(x^2+y^2)
=(x-y)(x+y)(x^2+y^2), (x^2+y^2) cannot be factored any because it is the sum of squares which is always prime
2). 6x^2 - xy - 12y^2
=(6x^2-9xy)+(8xy-12y^2)
=3x(2x-3y)+4y(2x-3y)
=(3x+4y)(2x-3y)
3).12(x+y)^2 + 8(x+y) - 15 (i did this but i'm not too sure if it is correct)
=12(x+y)(x+y) +8x+8y-15
=12(x^2+2xy+y^2)+8x+8y-15
=12x^2+24xy+12y^2+8x+8y-15

Answer 2

A great site to for Homework help is BeeHive. You pick your grade level then Math, then what type of math problem, etc. etc.

Hope this helps you.