а) (6a+2b)^2 = (6a+2b)(6a+2b) = 36a^2 + 12ab + 12ab + 4b^2 = 36a^2 + 24ab + 4b^2
б) (2x-5)^2 = (2x-5)(2x-5) = 4x^2 - 10x - 10x + 25 = 4x^2 - 20x + 25
в) (7a+2b)(2b-7a) = 7a2b - 7a7a + 2b2b - 2b*7a = 14ab - 49a^2 + 4b^2 - 14ab = -49a^2 + 4b^2
г) (2n^2+n)*(-2n^2+n) = -4n^4 - 2n^3 + 2n^3 + n^2 = -4n^4 + n^2
а) (6a+2b)^2 = (6a+2b)(6a+2b) = 36a^2 + 12ab + 12ab + 4b^2 = 36a^2 + 24ab + 4b^2
б) (2x-5)^2 = (2x-5)(2x-5) = 4x^2 - 10x - 10x + 25 = 4x^2 - 20x + 25
в) (7a+2b)(2b-7a) = 7a2b - 7a7a + 2b2b - 2b*7a = 14ab - 49a^2 + 4b^2 - 14ab = -49a^2 + 4b^2
г) (2n^2+n)*(-2n^2+n) = -4n^4 - 2n^3 + 2n^3 + n^2 = -4n^4 + n^2