А) (2х-1)^2 б) (3а+с)^2 в) (y-5)(y+5) г)(4b+5c)(4b-5c)

(2x - 1)^2 = 4x^2 - 4x + 1 (3a + c)^2 =9a^2 + 6ac + c^2 (y - 5)(y + 5) = y^2 - 25 (4b + 5c)(4b - 5c) = 16b^2 - 25c^2