1. Выполните действия: a) 15y²+7y-(13y-5y²); б) 2c (a-3b+4); в) (4x-1) (2x-3); г) (a+2) (a²-а-3); д) (4ab²-6a²b):2ab.

a) $$15y^2 + 7y - (13y - 5y^2) = 15y^2 + 7y - 13y + 5y^2 = (15y^2 + 5y^2) + (7y - 13y) = 20y^2 - 6y$$

б) $$2c(a - 3b + 4) = 2c cdot a - 2c cdot 3b + 2c cdot 4 = 2ac - 6bc + 8c$$

в) $$(4x - 1)(2x - 3) = 4x cdot 2x - 4x cdot 3 - 1 cdot 2x + 1 cdot 3 = 8x^2 - 12x - 2x + 3 = 8x^2 - 14x + 3$$

г) $$(a + 2)(a^2 - a - 3) = a cdot a^2 - a cdot a - a cdot 3 + 2 cdot a^2 - 2 cdot a - 2 cdot 3 = a^3 - a^2 - 3a + 2a^2 - 2a - 6 = a^3 + (-a^2 + 2a^2) + (-3a - 2a) - 6 = a^3 + a^2 - 5a - 6$$

д) $$(4ab^2 - 6a^2b) : 2ab = \frac{4ab^2}{2ab} - \frac{6a^2b}{2ab} = 2b - 3a$$