(m^4-n^4)(m^4+n^4)-m^6(m^2-n^2)-m^6n^2

Question

(m^4-n^4)(m^4+n^4)-m^6(m^2-n^2)-m^6n^2

Answer 1

(m^4-n^4)(m^4+n^4)-m^6(m^2-n^2)-m^6n^2=m^8-n^8-m^8+m^6n^2-m^6n^2=-n^8