Respuesta :

64 m^2  - 9 n^2 -------(1)
 first think about squares
 what is 64 m^2 = ( 8m)^2
also what is 9n^2 = (3n)^2
so  64 m^2  - 9 n^2  = (8m)^2 - (3n)^2
                                = (8m -3n) (8m+3n) ------(2)
to check multiply (2) to get (1)