Solve the separable equation y′=x/yy' = x/yy′=x/y.
y2−x2=Cy^2 - x^2 = Cy2−x2=C
y2+x2=Cy^2 + x^2 = Cy2+x2=C
y=x+Cy = x + Cy=x+C
y=Cxy = Cxy=Cx