Ответ:

  1. \(-m^4(-5m^3n^2)^4=-m^4\cdot625m^{12}n^8=-625m^{16}n^8\).
  2. \((-2x^3y^4)^5=(-2)^5x^{15}y^{20}=-32x^{15}y^{20}\).
  3. \(4a^3b^5a^6b^4=4a^{3+6}b^{5+4}=4a^9b^9\).