We have a function $h(x, y) = \ln(x^2 - y) + x^2y + 4 \cos(\pi(y - x))$ in two variables.
First we want to show that $h(x, y) = 8$ can be solved for $y$ in point $(2, 3)$. This is an implicit function and want can define it explicitly.
Next, we take that function for $y$ and want to get the tangential line at level 8 in that same point $(2, 3)$.
How to do that?