[8abˆ（1/3）-b(4/3)]/[4a^(2/3)+2(ab)^(1/3)+b^(2/3)]÷{[2（a/b）ˆ（1/3）]-1}﹡[bˆ（1/3）]
=[8ab^(1/3)-b^(4/3)]/[4a^(2/3)+2(ab)^(1/3)+b^(2/3)]×{[b^(1/3)]/2a^(1/3)-b^(1/3)}×b^(1/3)
=[8ab^(1/3)-b^(4/3)]/[4a^(2/3)+2(ab)^(1/3)+b^(2/3)]×[b^(2/3)]/2a^(1/3)-b^(1/3)
=(8ab-b^2)/[8a+4a^(2/3)b^(1/3)+2a^(1/3)b^(2/3)-4a^(2/3)b^(1/3)-2a^(1/3)b^(2/3)-b
=(8ab-b^2)/(8a-b)
=b