Differential Equation: $ye^{xy} dx + xe^{xy} dy = 0$

$ye^{xy}\,dx + xe^{xy}\,dy = 0$

$e^{xy}(y\,dx + x\,dy) = 0$

$e^{xy} \, d(xy) = 0$

$\displaystyle \int e^{xy} \, d(xy) = 0$

$e^{xy} = c$           answer