bjr

x² + 6x + 9 = (x + 3)²

(x + 3)² = 0

si x + 3 = 0 => x = -3

x² - 2x + 1 = 0

(x - 1)² = 0

x = 1

25x² - 9 = 0

(5x)² - 3² = 0

(5x + 3) (5x - 3) = 0

x = -3/5 ou x = 3/5

4x² + 2x = 0

2x (2x + 1) = 0

soit 2x = 0 => x = 0

soit 2x + 1 = 0 => x = -1/2

(4+x) (x+2) + 3 (4+x) = 0

(4+x) (x+2 + 3) = 0

(4+x) (x+5) = 0

soit 4+x = 0 => x = -4

soit x + 5 = 0 => x = -5

16x² - 8x = 0

8x (2x - 1) = 0

soit 8x = 0 => x = 0

soit 2x - 1 = 0 => x = 1/2