Question

(a + b - c)(a + b + c)

Answer 1

distribute it

Answer 2

let a+b=x,
then, (x+c)*(x-c)
=xsquared-csquared
=(a+b)squared- c squared
asquared+2ab+b squared- c squared

Answer 3

I come up with a^2-b^2-c^2+2bc but its wrong

Answer 4

chek mine; a^2+2ab+b^2-c^2

Answer 5

It fits....Thanks Mjbmanny very much :D