(a^4/3-8a^1/3b)/a^2/3+2(ab)^1/3+4b^2/3/(1-2(b/a)^1/3)*a^1/3
=[a^1/3(a-8b)]/[a^2/3+2(ab)^1/3+4b^2/3]÷[1-(2b^1/3/a^1/3)]*a^1/3
=[a^1/3(a^1/3-2b^1/3)(a^2/3+2a^1/3b^1/3+4b^2/3)]/[a^2/3+2(ab)^1/3+4b^2/3]÷[(a^1/3-2b^1/3)/a^1/3]*a^1/3
=[a^1/3(a^1/3-2b^1/3)*[a^1/3/(a^1/3-2b^1/3)]*a^1/3
=a^(1/3+1/3+1/3)
=a