一、答：已知y=x-1,则y+1=x,x-y=1,y-1=x-2
x²-2xy+3y²-2
=(x-y)²+2(y²-1)
=(x-y)²+2(y-1)(y+1)
=1+2x(x-2)
=2x²-4x+1
二、答：2x-14xy-2y/x-2xy-y
=6