∵x1,x2是方程的·两个根
∴x1x2=c/a=-3/2
x1+x2=-b/a=3
(1)x1x2(x1+x2)
=-3/2*3
=-9/2
(2)1/x1-1/x2=(x2-x1)/x1x2
=√(x2+x1)²-4x1x2/x1x2
=√9+6/(-3/2)
=√15/(-3/2)
=-2√15/2或2√15/2【1】题，c等于3吧？应该是3/2吧。额。看错（1）x1x2/(x1+x2)=3/2*3=9/2(2)同理√(x2+x1)²-4x1x2/x1x2=√9-4*3/2/(3/2)=√2/(3/2)=2√2/3或-2√2/3