(4m+7)(7-4m)-(4m-7)^2=-16m^2+49-16m^2+56m-49=-32m^2+56m
(5a+2)^2-(3+5a)(5a-3)=25a^2+20a+4+9-25a^2=20a+13
(4m+7)(7-4m)-(4m-7)^2=-16m^2+49-16m^2+56m-49=-32m^2+56m
(5a+2)^2-(3+5a)(5a-3)=25a^2+20a+4+9-25a^2=20a+13