Réponses

2014-10-19T20:43:08+02:00
C= (5-x) (2x-3x+8)
 = (5-x) (-X+8)

D= (7-2x) (3x-4-7+2x)
  = (7-2x)(5x-11)
Meilleure réponse !
2014-10-19T20:48:23+02:00
2(5-x)x-(5-x)(3x-8)
=(10-2x)x-(15x-40-3x²+8x)
=10x-2x²-7x+40+3x²
=3x+x²+40
(7-2x)(3x-4)-(7-2x)²
=(7-2x)(3x-4-7-2x)
=(7-2x)(x-11)
=7x-77-2x²+22x
=29x-2x²-77