Question

How would you start to simplify:

a^4-256

I know that 4^4=256, but I don't know what to do with this ..

Answer 1

(a^2-16)(a^2+16)
(a-4)(a+4)(a^2+16)

now, if you include imaginary numbers, letting j = sqrt(-1), then
(a-4)(a+4)(a+4j)(a-4j)