Sagot :
B=6a-8a²-15+20a-10+2a
=-8a²+28a-25
C=-3z+6+4z²-8z
=4z²-11z+6
D=-10r+15r²-2r²-5r-4r-10
=13r²-19r-10
voila
Développer et réduire :
B = (2a-5) (3-4a) - 2(5-a)
C = - (3-4z) (z-2)
D = -5r (2-3r) + (-r-2) (2r+5)
B=6a-8a²-15+20a-10+2a
=-8a²+28a-25
C=-3z+6+4z²-8z
=4z²-11z+6
D=-10r+15r²-2r²-5r-4r-10
=13r²-19r-10
voila