x² - 4x + 1 = 0 => (x² - 4x + 4 ) - 4 + 1 = 0 => (x-2)² - 3 = 0 =>
(x-2) = -√3 => x = 2 + √3 ou x-2 = √3 => x = 2 + √3
Exercice 2:
1. x²-6x +5=0 => (x² - 6x + 9) - 9 + 5 = 0 => (x- 3)² - 4 = 0
(x-3)² = 4 => x-3 = -2 => x = 1 ou x-3 = 2 => x = 5
2. 1/2x +3 = 3/4x +5
-1/4x = 2 => x = -8
bonne journée