Такой вопрос.  (2a - 3b + c^2 - d)^2

(2a – 3b + c^2 – d)^2 = (2a – 3b)^2 + 2 * (2a – 3b) * (c^2 – d) + (c^2 – d)^2 = 4a^2 – 12ab + 9b^2 + 2(2ac^2 – 2ad – 3bc^2 + 3bd) + c^4 – 2c^2d + d^2 = 4a^2 – 12ab + 9b^2 + 4ac^2 – 4ad – 6bc^2 + 6bd + c^4 – 2c^2d + d^2.