Use implicit differentiation where LaTeX:  \displaystyle y is a function of LaTeX:  \displaystyle x to find the derivative of LaTeX:  \displaystyle \sqrt{2} \sqrt{x} e^{y} + \log{\left(y \right)} \sin{\left(x^{3} \right)}=-18

Taking the derivative of both sides using implicit differentiation gives: LaTeX:   \sqrt{2} \sqrt{x} y' e^{y} + 3 x^{2} \log{\left(y \right)} \cos{\left(x^{3} \right)} + \frac{y' \sin{\left(x^{3} \right)}}{y} + \frac{\sqrt{2} e^{y}}{2 \sqrt{x}} = 0  Solving for LaTeX:  \displaystyle y' gives LaTeX:  \displaystyle y' = - \frac{y \left(6 x^{\frac{5}{2}} \log{\left(y \right)} \cos{\left(x^{3} \right)} + \sqrt{2} e^{y}\right)}{2 \sqrt{x} \sin{\left(x^{3} \right)} + 2 \sqrt{2} x y e^{y}}