[（a+b)/(2a）]^3÷[(a^2-b^2)/(ab^3)]^2
=[(a+b)^3/(8a^3)]÷[(a^2-b^2)^2/(a^2b^6)]
=a^2b^6(a+b)^3/[(8a^3)(a+b)^2(a-b)^2]
=b^6(a+b)/[8a(a-b)^2]