Use implicit differentiation where LaTeX:  \displaystyle y is a function of LaTeX:  \displaystyle x to find the derivative of LaTeX:  \displaystyle - 6 \sqrt{2} x^{3} \sqrt{y} - 8 \log{\left(y \right)} \sin{\left(x \right)}=-29

Taking the derivative of both sides using implicit differentiation gives: LaTeX:   - \frac{3 \sqrt{2} x^{3} y'}{\sqrt{y}} - 18 \sqrt{2} x^{2} \sqrt{y} - 8 \log{\left(y \right)} \cos{\left(x \right)} - \frac{8 y' \sin{\left(x \right)}}{y} = 0  Solving for LaTeX:  \displaystyle y' gives LaTeX:  \displaystyle y' = - \frac{18 \sqrt{2} x^{2} y^{2} + 8 y^{\frac{3}{2}} \log{\left(y \right)} \cos{\left(x \right)}}{3 \sqrt{2} x^{3} y + 8 \sqrt{y} \sin{\left(x \right)}}