Originally Posted by

**lausalas** hi, im doing this factoring assignment, and i cant figure out some of the problems , i'd be extremely glad if someone could help me.

(2m+8)^2 - (4m+5)^2 I have no idea how to start with this one

(2m+8)*(2m+8)-((4m+5)*(4m+5))

foil these out and then simplify.

x^2 - 21x -72

look for terms that multiply to -72 but add to -21

(x- )(x+ )

(x-2)^2 -16 Is this one a difference of squares? and how do

i resolve it?

if you had (x^2-9) this would also be a difference of squares and it would factor to (x+3)(x-3)=0

25x^2 +30xy + 9y^2 is this a tough polynomial? because i have no

idea how to resolve it, i got confused, or should i

resolve it using common factoring, only i've tried that and didnt work...