先算1/2的平方=1/4在开三次方
=3次根号4分之1=2分之3次根号2
(1/2)^(2/3)=(2^(-1))^(2/3)=2^(-2/3)=1/2^(2/3)=1/4^(1/3)=4^(2/3)/(4^(1/3)x4^(2/3)=16^1/3/4^(1/3+2/3)=16^1/3/4
