8a^(-1/3)根号b^(1/3)a^4根号b^(2/3)
=8a^(-1/3)根号b^(1/3)a^4根号b^(2/3)
=8a^(-1/3+4)根号b^(1/3+2/3)
=8a^(11/3)根号b
=8a^(11/3)b^(1/2)