Ответ:

  1. \(6a^3b^7=(-2ab^3)\cdot(-3a^2b^4)\).
  2. \(-\frac12ab^4=(-2ab^3)\cdot\frac14b\).
  3. \(3.2a^5b^3=(-2ab^3)\cdot(-1.6a^4)\).
  4. \(2\frac49a^{15}b^9=(-2ab^3)\cdot\left(-\frac{11}{9}a^{14}b^6\right)\).