Ответ:

  1. \(5n\cdot2n^2-5n\cdot3n=10n^3-15n^2\).

  2. \((-2d^2)\cdot4d+(-2d^2)\cdot(-9)=-8d^3+18d^2\).

  3. \(6h\cdot\frac12h^2-6h\cdot3h=3h^3-18h^2\).

Ответ: 1) \(10n^3-15n^2\); 2) \(-8d^3+18d^2\); 3) \(3h^3-18h^2\).