помогите пж! срочно
1. (m^2+3n)^2
2. m^3-n^9
3.(4m-7n)^2

1. (m^2+3n)^2=m^4+6m^2n+9n^2; 2. m^3-n^9=(m-n^3)*(m^2+mn^3+n^6); 3. (4m-7n)^2=16m^2-56mn+49n^2.