Помогите! вообще не соображаю.. Реши уравнение (9x−3)^2−(x−11)^2=0 Ответ: x1= x2=

Решите задачу:

$(9x - 3 {)}^{2} - (x - 11 {)}^{2} = 0 \\ 81 {x}^{2} - 54x + 9 - ({x}^{2} - 22x + 121) = 0 \\ 81 {x}^{2} - 54x + 9 - {x}^{2} + 22x + - 121 = 0 \\ 80 {x}^{2} - 32x - 112 = 0 \\ 16 \times (5 {x}^{2} - 2x - 7) = 0 \\ 16 \times (5 {x}^{2} + 5x - 7x - 7) = 0 \\ 16 \times (5x(x + 1) - 7 \times (x + 1)) = 0 \\ 16 \times (x + 1) \times (5x - 7) = 0 \\ (x + 1) \times (5x - 7) = 0 \\ x + 1 = 0 \\ 5x - 7 = 0 \\ x 1= - 1 \\ x2 = \frac{7}{5} = 1.4$