Question

3(m^2-n^2)+(m-n)(m+n)

Answer 1

3(m^2-3n^2)+(m-n)(m+n)

3m^2-3n^2+(m-n)(m+n)

3m^2-3n^2+m^2-n^2

4m^2-3n^2-n^2

4m^2-4n^2

Answer 2

3(m^2-n^2)+(m-n)(m+n)=
=3m^2-3n^2+m^2-n^2=4m^2-4n^2