Use implicit differentiation where $LaTeX: \displaystyle y$ is a function of $LaTeX: \displaystyle x$ to find the derivative of $LaTeX: \displaystyle - \log{\left(y \right)} \cos{\left(x^{2} \right)} + 6 \sin{\left(x^{2} \right)} \cos{\left(y^{2} \right)}=-38$

Taking the derivative of both sides using implicit differentiation gives: $LaTeX: 2 x \log{\left(y \right)} \sin{\left(x^{2} \right)} + 12 x \cos{\left(x^{2} \right)} \cos{\left(y^{2} \right)} - 12 y y' \sin{\left(x^{2} \right)} \sin{\left(y^{2} \right)} - \frac{y' \cos{\left(x^{2} \right)}}{y} = 0$ Solving for $LaTeX: \displaystyle y'$ gives $LaTeX: \displaystyle y' = \frac{2 x y \left(\log{\left(y \right)} \sin{\left(x^{2} \right)} + 6 \cos{\left(x^{2} \right)} \cos{\left(y^{2} \right)}\right)}{12 y^{2} \sin{\left(x^{2} \right)} \sin{\left(y^{2} \right)} + \cos{\left(x^{2} \right)}}$