Réponses

2013-11-03T13:11:55+01:00
(x+2)²-49 = (x+2)²-7² = [(x+2)-7] [(x+2)-7]= (x-5)(x+9) 
2013-11-03T13:15:07+01:00
(x+2)^2- 7^2 = A^2 - B^2 identité remarquable