(2a + 8b)^2 = (2a + 8b)(2a + 8b) = 4a^2 + 16ab + 16ab + 64b^2 = 4a^2 + 32ab + 64b^2
(3 - 9x)^2 = (3 - 9x)(3 - 9x) = 9 - 27x - 27x + 81x^2 = 9 - 54x + 81x^2
(2a + 8b)^2 = (2a + 8b)(2a + 8b) = 4a^2 + 16ab + 16ab + 64b^2 = 4a^2 + 32ab + 64b^2
(3 - 9x)^2 = (3 - 9x)(3 - 9x) = 9 - 27x - 27x + 81x^2 = 9 - 54x + 81x^2