x = - 3
Объяснение:
(х - 7)(х + 7) - (х + 10)(х - 1) = 4х
x² - 49 - (х + 10)(х - 1) = 4х
x² - 49 - (x² - x + 10x - 10) = 4х
x² - 49 - (x² + 9x - 10) = 4х
x² - 49 - x² - 9x + 10 = 4х
- 49 - 9x + 10 = 4x
-39 - 9x = 4x
-9x - 4x = 39
- 13x = 39
x = 39 : (- 13)
x = - 3
