(у-4)^2 = y^2 - 8y + 16
(7x+a)^2 = 49x^2 + 14ax + a^2
(5c-1)(5c+1) = 25c^2 - 1
(3a+2b)(3a-2b) = 9a^2 - 4b^2
(у-4)^2 = y^2 - 8y + 16
(7x+a)^2 = 49x^2 + 14ax + a^2
(5c-1)(5c+1) = 25c^2 - 1
(3a+2b)(3a-2b) = 9a^2 - 4b^2