Réponses

2013-11-11T22:17:50+01:00
A=(x+3)-(x+5)-(x -7)
=x+3-x-5-x+7
=-x+5

B= -(a+4)+( a+5)+(3-a)
=-a-4-a+5+3-a
=-3a+4

C=-(x²-x)-(x-1)-(1-x²)
=-x²+x-x+1-1+x²
=0

D=x²-(3x²-5x²)+(x²-8x²)-2x²
=x²-3x²+5x²+x²-8x²-2x²
=-6x²