Sagot :
This is a special product since:
[tex](a-b)^2=a^2-2ab+b^2 \\ (7q^2m^2-4w^2)^2=49q^4m^4-56q^2m^2w^2+16w^4[/tex]
[tex](a-b)^2=a^2-2ab+b^2 \\ (7q^2m^2-4w^2)^2=49q^4m^4-56q^2m^2w^2+16w^4[/tex]