bonjour
(2 x - 5)² = 4 ( x - 1) ( x +1)
4 x² - 20 x + 25 = ( 4 x - 4) ( x - 1)
4 x² - 20 x + 25 = 4 x² - 4 x - 4 x + 4
4 x² - 20 x - 4 x² + 4 x + 4 x = 4 - 25
- 12 x = - 21
x = 21/12 = 7/4 = 1.75
4 x - 3 ( 2 + x² ) = ( 2 x + 1)² - 7 ( x - 1)²
4 x - 6 - 3 x² = 4 x² + 4 x + 1 - 7 ( x² - 2 x + 1)
= - 3 x² + 4 x - 6 = 4 x² + 4 x + 1 - 7 x² + 14 x - 7
= - 3 x² + 4 x - 4 x² - 4 x + 7 x² - 14 x = - 7 - 1 + 6
= - 14 x = - 2
x = 2/14 = 1/7