Réponses

2013-12-02T01:17:13+01:00
B=(2x-3)²-(2x-3)(x+1)    
développement:
B= 4 x^2 - 12x +9 - 2x^2 -2x +3x +3 = 2x^2 -11x +12

Pour x=4
B= 32-44+12= 0

2013-12-02T01:18:54+01:00
Bonsoir,

1/ B = (2x - 3)² - (2x - 3)(x + 1) 
B = (4x² - 12x + 9) - (2x² + 2x - 3x - 3)
B = (
4x² - 12x + 9) - (2x² - x + 3)
B = 4x² - 12x + 9 - 2x² + x - 3
B = 2x² -11x +12

2/ 2 * 4² - 11 * 4 + 12 
= 2 * 16 - 44 + 12
= 32 - 44 + 12
= 0