а) (5a-6b)(6b-5a) = 5a6b + 5a(-5a) - 6b6b - 6b(-5a) = 30ab - 25a^2 - 36b^2 + 30ab = 60ab - 25a^2 - 36b^2б) (x-y)(x+y)(x-y) = (x^2 - y^2)(x-y) = x^2x - x^2y - y^2x + y^2y = x^3 - x^2*y - xy^2 + y^3
а) (5a-6b)(6b-5a) = 5a6b + 5a(-5a) - 6b6b - 6b(-5a) = 30ab - 25a^2 - 36b^2 + 30ab = 60ab - 25a^2 - 36b^2
б) (x-y)(x+y)(x-y) = (x^2 - y^2)(x-y) = x^2x - x^2y - y^2x + y^2y = x^3 - x^2*y - xy^2 + y^3