根号下3根号下3根号下3
=(3根号下3根号下3)^(1/2)
=3^(1/2)*(3根号下3)^(1/4)
=3^(1/2)*3^(1/4)*3^(1/8)
=3^(1/2 +1/4 +1/8)
=3^(7/8)
所求=7/8