Question

How do I factor x^4+81
I know that x=3i but I need the factoring. Any help is welcomed. :)

Answer 1

I assume you are familiar with:

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

Answer 2

\(x^4 + 81\)

\(= x^4 - (-81)\)

\(= (x^2)^2 - (9i)^2\)

\(= (x ^2 + 9i)(x^2 - 9i)\)

Answer 3

Oh thank you so much. I have been dealing with figuring too much out. This helps greatly!

Answer 4

It's not done, though. Now it gets more complicated.

Answer 5

That is fine I just needed the start. :) I am having to solve with the imaginary and real parts. If I run into trouble I may hit you up. ;)