Sagot :
B= -4(-5x+9)
5x=-4+9
5x=5
x=5/5=1
C= 2(x+3) -7(3x-5)
=2x+6-21x +35
-2x+21x=6+35
19x=41
x=41/19
D= (x+7)(x+3)
2x=21
x=21/2
E= (2x+1)(3x-2)
6x=-1
x=-6
Le deuxieme j'ai pas trop compri :s
B= -4(-5×9)=-4×-5+-4×9=20+-36=-16
C= 2(x+3)-7(3×-5)=(2x+2×3)-(7×3-7×5)=(2x+6)-(-14)=2x-20