a^2+6a+9分之a^2-9/(1-a分之3)

问题描述:

a^2+6a+9分之a^2-9/(1-a分之3)

a^2+6a+9分之a^2-9/(1-a分之3)
=[(a+3)(a-3)/(a+3)^2]/[(a-3)/a]
=(a-3)/(a+3)*a/(a-3)
=a/(a+3)