由韦达定理：x1+x2=3/2 x1x2=1/2
(1)(x1-1)(x2-1)=x1x2-(x1+x2)+1=3/2-1/2+1=2
(2)x2/(x1+1)+x1/(x2+1)
=[x2(x2+1)+x1(x1+1)]/[(x1+1)(x2+1)]
=[x1²+x2²+(x1+x2)]/[x1x2+(x1+x2)+1]
=[(x1+x2)²-2x1x2+3/2]/(1/2+3/2+1)
=[(3/2)²-2*1/2+3/2]/3
=11/12
由韦达定理：x1+x2=3/2 x1x2=1/2
(1)(x1-1)(x2-1)=x1x2-(x1+x2)+1=3/2-1/2+1=2
(2)x2/(x1+1)+x1/(x2+1)
=[x2(x2+1)+x1(x1+1)]/[(x1+1)(x2+1)]
=[x1²+x2²+(x1+x2)]/[x1x2+(x1+x2)+1]
=[(x1+x2)²-2x1x2+3/2]/(1/2+3/2+1)
=[(3/2)²-2*1/2+3/2]/3
=11/12