\textbf{138-} By rotating the coordinate axes by an appropriate angle, the equation of the hyperbola $\sqrt{3}\,xy + y^2 = 1$ is written in which form?
(1) $3x^2 - y^2 = 2$ \qquad (2) $2x^2 - 3y^2 = 2$ \qquad (3) $3x^2 + y^2 = 2$ \qquad (4) $2x^2 + 3y^2 = 2$