[(2x+1)/(x+y) - (2xy+y)/(y方－x方)]=[(2x+1)(y-x)/(y^2-x^2) - y(2x+1)/(y^2-x^2)]=(2x+1)(y-x-y)/(y^2-x^2)=-x(2x+1)/(y^2-x^2)(x-y)/(2x+1) * [(2x+1)/(x+y) - (2xy+y)/(y方－x方)]+y/(x+y)=(x-y)/(2x+1) * [-x(...