Réponses

2013-05-01T15:23:06+02:00

1) E=(4x+5)²-(3x-2)²

      = (16x²+40x+25)-(9x²-12x+4)

      = 16x²+40x+25-9x²+12x-4

      = 7x²+52x+21

 

2)E=7x²+52x+21

      = (7x+3)(x+7)

 

3) (7x+3)(x+7)=0

     7x+3=0        et         x+7=0

      7x=-3           et         x=-7

       x= -3/7        et            x= -7