(х - 3) * (х² + 3х + 9) - х * (х + 5) * (х - 5) = 23
х³ - 27 - х * (х² - 25) = 23
х³ - 27 - х³ + 25х = 23
- 27 + 25х = 23
25х = 23 + 27
25х = 50
х = 2
(5 - х)² - х * (2,5 + х) = 0
25 - 10х + х² - 2,5х - х² = 0
25 - 12,5х = 0
- 12,5х = - 25
