(2x-4)(x-11)+28 = 2x^2 - 22x - 4x + 44 + 28 = 2x^2 - 26x + 72 = 0
x^2 - 13x + 36 = 0
D = b^2 - 4ac = (-13)^2 - 4 \cdot 1 \cdot 36 = 169 - 144 = 25
x_1 = \frac{-b + \sqrt{D}}{2a} = \frac{13 + \sqrt{25}}{2} = \frac{13 + 5}{2} = \frac{18}{2} = 9
x_2 = \frac{-b - \sqrt{D}}{2a} = \frac{13 - \sqrt{25}}{2} = \frac{13 - 5}{2} = \frac{8}{2} = 4
Ответ: 49