$\quad f(x,y)= y\ln(\sin x) + xe^{x^2-y}$
Ta có:
$+)\quad \dfrac{\partial f}{\partial x}= y\cdot \dfrac{\cos x}{\sin x} + e^{x^2-y} + 2x^2e^{x^2-y}$
$= y\cot x + (2x^2 +1)e^{x^2 -y}$
$+)\quad \dfrac{\partial f}{\partial y}=\ln(\sin x) - xe^{x^2 - y}$