Answer
$y=x+2$
Work Step by Step
We have: $xy-y^2 =x^2-3$
We differentiate both sides with respect to $x$.
$x\dfrac{dy}{dx} -2 y\dfrac{dy}{dx} =2x-y\\ \dfrac{dy}{dx} =\dfrac{2x-y}{x-2y}$
The equation of a tangent line at $(-1,1)$ is:
$y-y_1=m(x-x_1)\\ y-1=1(x+1) \\ y=x+2$
