а) (а+b)^4 = a^2 + 4a^3b + 6a^2b^2 + 4ab^3 + b^4 б) (x+y)^5 - (x-y)^5 = x^5 + 5x^4y + 10x^3y^2 + 10x^2y^3 + 5xy^4 + y^5 - x^5+ 5x^4y- - 10x^3y^2 + 10x^2y^3 - 5xy^4 + y^5 = 10x^4y + 20x^2y^3 + 2y^5