Factorising the following expression:
X^2 + 8x + 4 - y^2
Which method of factorising is the most appropriate? Cheers

Question

mertsj · Answer

Not factorable

anonymous · Answer

I think the "completing the square" method is your best option. So:
$$=x ^{2}+8x+(8\div2)^{2}-(8\div2)^{2}-y^{2}$$
$$=(x+4)^{2}-4^{2}-y ^{2}+4$$
$$=(x+4)^{2}-y^{2}-4^{2}+4$$
$$=(x+4-y)(x+4+y)-12$$
And I think that's it. There's not much else you can do.

mertsj · Answer

Bit that is not factored!!

mertsj · Answer

We may as well write x(x+8)-(y-2)(y+2)

anonymous · Answer

Well it depends on the problem Chad123 is trying to solve. I understand it is not "fully" factorized, but perhaps it will help them anyway.

anonymous · Answer

Thanks guys for your help. I'll give each one of you a medal :)