Aidez moi SVP : exercice 4

A=2x+3-5x+7
=-3x+10

B=-6a+2a²-3a-a²
=a²-9a

C=-4x+6x²-5-3x²+6x
=3x²-2x-5

D=3-5a+7-10+8a-3a
=0

E=-7n+12n-3+4n-8
=9n-11

F=6a²+3ab -9a²+9ab-a²
=-4a²+12ab