Vous pourriez m aider c l algèbre je n arrive pas du tout

Bonjour

II) a)
A=(25×27)/(72×75)= 0,125=1,25×10^(-1)=1/8

b)
B= (3/5-1/4)/(1+2/5)= (12/20-5/20)/(5/5+2/5)= (7/20)/(7/5)= 7/20 × 5/7 = (7×5)/(20×7)= 5/20 = (5×1)/(5×4)= 1/4

c)
ab^2=3×(-2)^2=3×4=12
(ab)^2=(3×(-2))^2=(-6)^2=36
ab^3=3×(-2)^3=3×(-8)=-24
(ab)^3=(3×(-2))^3=(-6)^3=-216
a^(-2)=3^(-2)=1/(3^2)=1/9
a×10^-3=3×10^-3=0,003
b^(-3)=(-2)^(-3)=1/((-2)^3)=1/(-8)=-1/8