Question

How do I get all the solutions for x^8-256=0

Answer 1

you want 8 solutions?

Answer 2

that equation has 2 real solutions , x ={2, -2}. and 6 non real solutions

Answer 3

http://www.wolframalpha.com/input/?i=factor+x%5E8-256

Answer 4

You get
\[
x^8-256=(x-2) (x+2) \left(x^2+4\right) \left(x^4+16\right)
\]
You can finish it from here to find the 6 complex roots

Answer 5

In addition to the real ones 2 and -2