(m+n)(m-n)(m2-n2)+2m2n2

Question

(m+n)(m-n)(m2-n2)+2m2n2

Answer 1

(m+n)(m-n)(m²-n²)+2m²n²=(m²-n²)(m²-n²)+2m²n²=(m²-n²)²+2m²n²=
=m⁴-2m²n²+n⁴+2m²n²=m⁴+n⁴.