$$\frac{\partial z}{\partial x} = 8x$$ | $$\frac{\partial z}{\partial y} = 6y$$ |
$$\frac{dx}{dt} = cos t$$ | $$\frac{dy}{dt} = -sen t$$ |
$$\frac{\partial z}{\partial x} = \frac{x}{\sqrt{x^2-y^2}}$$ | $$\frac{\partial z}{\partial y} = \frac{-y}{\sqrt{x^2-y^2}}$$ |
$$\frac{dx}{dt} = 2e^{2t}$$ | $$\frac{dy}{dt} = -e^{-t}$$ |