Given the curve with equation $y\!\left(y^{2}-1\right)\!\left(y-4\right) = x\!\left(x-1\right)\!\left(x-4\right)$, find equations of the tangent lines at the points $\left(0,-1\right)$ and $\left(4,4\right)$.

is an equation of the tangent line to the curve at the point $\left(0,-1\right)$.

is an equation of the tangent line to the curve at the point $\left(4,4\right)$.