Réponses

2014-01-11T14:42:46+01:00
1) -5(3x -2) 
=-15x+4

2) -(x +3)(2x-4)
=-(2x²-4x+6x-12)
=-2x²+4x-6x+12
=-2x²-2x+12

3) -3(4x-5)(2x+1)
=-3(8x²+4x-10x-5)
=-24x²-12x+30x+15
=-24x²+18x+15

4) (x+5)² +(-2+6)(x-7)
=x²+10x+25-2x+14+6x-42
=x²+14x-5

5) 3x (-x+5)-(5x-3)(x+8)
=-3x²+15x-(5x²+40x-3x-24)
=-3x²+15x-5x²-40x+3x+24
=-8x²-22x+24