How do you factor #7h^4-7p^4#?
When factorising :
1) Firstly, look for common factors
2) Secondly look for difference of squares
In this case
by inspection we see
now look for difference of squares
if both powers are even then we have DoS
now look and see if we can factorise anything further.
the first bracket can not be factorised using real numbers, but the second bracket is DoS again.
so we have
and that is now fully factorised.
***If you allow complex numbers then the first bracket can be factorised using DoS