I have graph $\displaystyle x^4+y^4+2=4xy^3$ and I need to findtanget equationat $\displaystyle (1;1)$ (on a graph) point.

I can't seem to get what to do with $\displaystyle x$s and $\displaystyle y$s can't convey neither of those

Do I need to do partial fluxion for $\displaystyle x$ and then for $\displaystyle y$? (well... these ones: $\displaystyle Fx'=...$ and $\displaystyle Fy'=...$ )

If yes, what should I do next with those 2 functions?