Respuesta :

1. 10m^5 +5m^4  - 25^2 = 5m^2(2m^3 + m^2 - 5)
2. x^2  - 18x + 81 = x^2 - 2*x*9 + 9^2 = (x - 9)^2
3. 9x^2 -49y^2 = (3x)^2 - (7y)^2 = (3x + 7y)(3x - 7y)