bonjour
x² + 6 x + 9 = 0
( x + 3 )² = 0 ⇔ x = - 3
1 + 8 x + 16 x² = 0
( 4 x + 1 ) ² = 0 ⇔ x = - 1/4
x² - 2 x + 1 = 0
( x - 1 )² = 0 ⇔ x = 1
x² - 16 = 0
( x - 4 ) ( x + 4 ) = 0 ⇔ x = 4 ou - 4
25 x² - 9 = 0
( 5 x - 3 ) ( 5 x + 3 )= 0 ⇔ x = 3/5 ou - 3/5
9 x² - 100 = 0
( 3 x - 10 ) ( 3 x + 10 ) = 0 ⇔ x = 10/3 ou - 10/3