Bonjour
M = (x - 3)^2 - 9
1) calculer M pour x = 6 :
M = (6 - 3)^2 - 9
M = 3^2 - 9
M = 9 - 9
M = 0
2) developper M :
M = x^2 - 6x + 9 - 9
M = x^2 - 6x
3) factoriser M :
M = (x - 3)^2 - 3^2
M = (x - 3 - 3)(x - 3 + 3)
M = (x - 6) * x
M = x(x - 6)
4) résoudre l’équation M = 0
x(x - 6) = 0
x = 0 ou x - 6 = 0
x = 0 ou x = 6
