а) 9x^2 - (y-3x)^2 = 9x^2 - (y^2 - 6xy + 9x^2) = 9x^2 - y^2 + 6xy - 9x^2 = 6xy - y^2
б) (5a+7)^2 - 70a = 25a^2 + 70a + 49 - 70a = 25a^2 + 49
в) c(1+2c)^2 = c(1 + 4c + 4c^2) = c + 4c^2 + 4c^3
г) -6(2x-y)^2 = -6(4x^2 - 4xy + y^2) = -24x^2 + 24xy - 6y^2
д) (p+7)*p - (1-p) = p^2 + 7p - 1 + p = p^2 + 8p - 1
а) 9x^2 - (y-3x)^2 = 9x^2 - (y^2 - 6xy + 9x^2) = 9x^2 - y^2 + 6xy - 9x^2 = 6xy - y^2
б) (5a+7)^2 - 70a = 25a^2 + 70a + 49 - 70a = 25a^2 + 49
в) c(1+2c)^2 = c(1 + 4c + 4c^2) = c + 4c^2 + 4c^3
г) -6(2x-y)^2 = -6(4x^2 - 4xy + y^2) = -24x^2 + 24xy - 6y^2
д) (p+7)*p - (1-p) = p^2 + 7p - 1 + p = p^2 + 8p - 1