Hi all,

why can't a^2+b^2 be factored in fact non of the following factor

a^4+b^4

a^8+b^8

a^16+b^16

the factors are all even numbers and some even factors can be broken up to to produce a prime number factor ie 10 become 2^5 but i can't quite see why these sums can't be factored.

Thanks for the help.