# Homework Help: Factoring over real numbers

1. Apr 10, 2012

### NewtonianAlch

1. The problem statement, all variables and given/known data
Factorise z$^{8}$ -15z$^{4}$ - 16 over the Complex numbers and Real numbers

3. The attempt at a solution

I factorised over the complex numbers, I'm not sure what they mean by over the real numbers.

Do I substitute z = (x + iy) and then do it by expanding and separating real from complex? I would have tried it at first, except these are powers to the 8, which seems like an unlikely method.

2. Apr 10, 2012

### tiny-tim

Hi NewtonianAlch!
over the complex numbers means that the factors have (possibly) complex coefficients (and will all be linear)

over the real numbers means that the factors have real coefficients (and will be either linear or quadratic)