Réponse:
A=(-2/5)^3=-2^3/5^5=-8/125
B=(-3/2)^-3
=-3^-3/2^-3
=-1/27 /1/8
=-1/27 x 8
=-8/27
C=(9/-5)^-1 x (4/5+1)
=9^-1/-5^-1 x 4+5/5
=1/9 /-1/5 x 9/5
= 1/9 x (-5) x 9/5
=-1
