Réponses

2014-10-27T15:42:24+01:00
X² = 9 => x² - 9 = 0 => (x-3)(x+3) = 0 => x = 3 ou x  =-3
2014-10-27T15:43:11+01:00
X²=9
x²-9 =0
(x-3)(x+3) = 0

x-3 = 0               et  x+3 =0
x = 3                 et x = -3
donc solution (3;-3)