Réponses

2013-04-03T19:53:11+02:00

D = (x - 5)² - 16

D = x² - 10x + 25 - 16

D = x² - 10x + 9

 

Factorisation :

D = (x - 5)² - 16

D = (x - 5 - 4)(x - 5 + 4)

D = (x - 9)(x - 1)

 

Si D = 0 alors

(x - 9)(x - 1) = (0 - 9)(0 - 1)

                     = -9 * (-1)

                     = 9