(x^2+1)(y^2+1)=4xyx^2y^2+x^2+y^2+1-4xy=0(x^2y^2-2xy+1)+(x^2+y^2-2xy)=0(xy-1)^2+(x-y)^2=0(xy-1)^2=0,(x-y)^2=0xy-1=0x-y=0解得x=y=1或x=y=-1当x=y=1时,x^2-3y+1=1-3+1=-1当x=y=-1时,x^2-3y+1=1+3+1=5所以x^2-3y...