Réponses

2013-11-17T13:03:42+01:00
A)25x²-30x+9=(5x)²-2*5x*3+(3)²=(5x-3)²

b)x²+20x+100=(x)²+2*x*10+(10)²=(x+10)²

c)9x²-1=(3x)²-1²=(3x+1)(3x-1)
2013-11-17T13:23:27+01:00
Bonjour
25x² -30x +9 = 5x² - 2 x 3 x 5 + 3²
x² +20x +100 = x² + 2 x 10 x x +10²
9x² -1 = 3x +1 x 3x -1