(1)x1²x2+x1x2² (2)x1²+x2²-3x1x2
韦达定理,X1+X2=-2,X1X2=-3/2
x1²x2+x1x2² =X1X2(X1+X2)=3
x1²+x2²-3x1x2=(X1+X2)^2-5x1x2=23/2