(3x-5a)*(5a-3x) = 15ax - 25a^2 - 9x^2 + 15ax = -25a^2 + 30ax - 9x^2
(3x - 5a)^2 = 9x^2 - 30ax + 25a^2
(3x-5a)^3 = 27x^3 - 3*9x^2*5a + 3*3x*25a^2 - 125a^3 =
= 27x^3 - 135x^2*a + 225x*a^2 - 125a^3
(3x-5y+2)^2 = 9x^2 - 30xy + 25y^2 + 12x - 20y + 4
(3x-5y)*(9x^2+15xy+25y^2) = 27x^3-45x^2*y+45x^2*y-75xy^2+75xy^2-125y^3 =
= 27x^3 - 125y^3