2x²-4x/x+2·x²+2x/x²-4x+4+4x/2-x
=2X(X-2)/(X+2)*X(X+2)/(X-2)^2-4X/(X-2)
=2X/(X-2)-4X/(X-2)
=-2X/(X-2)
当x=1/2时,
原式=-1/(-3/2)=2/3。
2x²-4x/x+2·x²+2x/x²-4x+4+4x/2-x
=2x(x-2)/(x+2)× x(x+2)/(x-2)²-4x/(x-2)
=2x²/(x-2)-4x/(x-2)
=(2x²-4x)/(x-2)
=2x
当x=1/2时
原式=1