你是说
³√3(³√(4/9)-³√(2/9)+³√(1/9))^(-1)=³√3/(³√(2/3)²-³√(2/3)(1/3)+³√(1/3)²)=³√3(³√(2/3)+³√(1/3))/[(³√(2/3)²-³√(2/3)(1/3)+³√(1/3)²)(³√(2/3)+³√(1/3))]=(³√3³√(2/3)+³√3³√(1/3))/(³√(2/3)³+³√(1/3)³)=(³√2+³√1)/(2/3+1/3)=(³√2+1)/(3/3)=³√2+1