б) (3m + n)^2 = (3m + n)(3m + n) = 9m^2 + 6mn + n^2
в) (5x - 7)(5x + 7) = 25x^2 - 49
г) (3d + 2y)(3d - 2y) = 9d^2 - 4y^2
б) (3m + n)^2 = (3m + n)(3m + n) = 9m^2 + 6mn + n^2
в) (5x - 7)(5x + 7) = 25x^2 - 49
г) (3d + 2y)(3d - 2y) = 9d^2 - 4y^2