(1)3.8
相反數(shù)=-3.8,
倒數(shù)=1/3.8=10/38=5/19
絕對(duì)值=3.8

(2)負(fù)根號(hào)下21
相反數(shù)=√21,
倒數(shù)=-1/√21=(-√21)/21
絕對(duì)值=√21

(3)負(fù)π
相反數(shù)=π,
倒數(shù)=1/π
絕對(duì)值=π

(4)根號(hào)下3
相反數(shù)=-√3,
倒數(shù)=1/√3=(√3)/3
絕對(duì)值=√3

(5)三次根號(hào)下1000分之27
相反數(shù)=-³√27/1000=-3/10,
倒數(shù)=1/(³√27/1000)=1/(3/10)=10/3
絕對(duì)值=³√27/1000=3/10