[x^2-y^2]/[x+y] -[ 4x(x-y)+y^2]/[2x-y]=[(x+y)(x-y)]/[x+y]-[4x^2-4xy+y^2]/[2x-y]=[x-y]-[2x-y]^2/[2x-y]=x-y-[2x-y]=-x
楼主是要化简吧？原式=x^2-y^2/2x - 4x^2+4xy=- 3x^2+4xy-y^2/2x
