Ответ:

  1. а) \(3x^my\cdot16x^8y^4=48x^{m+8}y^5\).
  2. б) \(-xy\cdot x^my^m=-x^{m+1}y^{m+1}\).
  3. в) \(-a^mc^m\cdot(-64a^6c^3)=64a^{m+6}c^{m+3}\).
  4. г) \(\frac17xy\cdot0{,}49x^{2n}y^2=0{,}07x^{2n+1}y^3\).
  5. д) \(-125x^{3n}y^6\cdot4x^4y=-500x^{3n+4}y^7\).
  6. е) \(-27a^3b^6\cdot a^{5n}=-27a^{5n+3}b^6\).
  7. ж) \(a^4c^{12n}\cdot(-a^{5n}b)=-a^{5n+4}b c^{12n}\).
  8. з) \(625a^2x^4\cdot\frac1{125}a^{3n}x^{3m}=5a^{3n+2}x^{3m+4}\).