[填空题]
The curve C is defin5f)e7w xj izk c b2r0*mvr(52l-sz coz:(k6l +k mmi, bsmm4fqed by the equation $x^{2} y+\ln (x y)=1$, x $\lt$0, y $\lt$0 .
1. Find $\frac{\mathrm{d} y}{\mathrm{~d} x}$ in terms of x and y .
2. Determine the equation of the tangent to C at the point $\mathrm{P}(1,1)$.
