解:原式=(a-1)^2/(a-1)-根号下(a-1)^2/a(a-1)
=a-1-根号下(a-1)^2/a(a-1)
当a=根号3时,a-1>0,根号下(a-1)^2=a-1
a-1-根号下(a-1)^2/a(a-1)
=a-1-(a-1)/a(a-1)
=a-1-1/a
=根号3-1-1/根号3
=2/3根号3-1
当a=-根号3时,a-1<0,根号下(a-1)^2=1-a
a-1-根号下(a-1)^2/a(a-1)
=a-1-(1-a)/a(a-1)
=a-1+1/a
=根号3-1+1/根号3
=4/3根号3-1
解:原式=(1-a)²/(a-1)-√(1-a)²/a(a-1)
当a=√3时,
(1-a)²/(a-1)-√(1-a)²/a(a-1)
=(√3-1)-1/√3
=√3-1-√3/3
=2√3/3-1
当a=-√3时,
(1-a)²/(a-1)-√(1-a)²/a(a-1)
=-(√3+1)+1/√3
=-(2√3/3+1)