# Math Help - factoring

1. ## factoring

I was just working on some Alg. problems when I was faced with this lil cute problem;

Factor out:

$r^4-4096$

Well after abusing the calculator I came to dropping the question till I was done with everything and was then given the answer.

$(r^2+64)(r+8)(r-8)$

Well I do hope all of you had a great Xmas and PLEASE have a berry safe New Years!!

See ya'll later!!!!

2. Originally Posted by Morzilla
I was just working on some Alg. problems when I was faced with this lil cute problem;

Factor out:

$r^4-4096$

Well after abusing the calculator I came to dropping the question till I was done with everything and was then given the answer.

$(r^2+64)(r+8)(r-8)$

Well I do hope all of you had a great Xmas and PLEASE have a berry safe New Years!!

See ya'll later!!!!
Hi Morzilla, this is a difference of perfect squares problem.

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

For this problem, we have

$r^4 - 4096= (r^2)^2 - (64)^2 = (r^2+64)(r^2-64)$

Then the second pair of brackets can be further factored:

$(r^2+64)(r^2-64) = (r^2+64)(r^2-(8)^2) = (r^2+64)(r+8)(r-8)$

3. yes your right, I never knew that $64^2$ was 4096, I would have never guessed and if I did it would have been way too late!!!

4. Originally Posted by Morzilla
yes your right, I never knew that $64^2$ was 4096, I would have never guessed and if I did it would have been way too late!!!

Yeah, I would start with a guess... say $60^2$, which I know is close, then eventually get more accurate..