Réponses

2012-11-04T17:35:42+01:00

bonsoir

(5x+3)² - (5x+3)(7x-2) = (5x+3)(5x+3) -(5x+3)(7x-2) = (5x+3)( 5x+3-7x+2)

= (5x+3)(-2x+5) forme factorisée 

= -10x² +25x -6x +15 = -10x² +19x +15

si x = 4

f(4)= -160 + 76 +15 = 69