Ответ:
- \(4x^2y-6x^2y^2=2x^2y(2-3y)\).
- \(5x^3-15x^2b+20ab^2=5(x^3-3x^2b+4ab^2)\).
- \(6mn^2-9n^3+12m^2n^2=3n^2(2m-3n+4m^2)\).
- \(-3xy^2-15x^2y-21x^2y^2=-3xy(y+5x+7xy)\).
- \(12a^2b-18ab^2-30ab^3=6ab(2a-3b-5b^2)\).
- \(-6ax^2+9x^2-12x^4-3a^2x^2=3x^2(-2a+3-4x^2-a^2)\).
