а) (2a - 5)2 = 4a2 - 20a + 25
б) (5 + 8m)2 = 25 + 80m + 64m2
в) (2a - 3) * (2a + 3) = 4a2 - 9
г) (5d + 2) * (5d - 2) = 25d2 - 4