$$\lim_{w\to0}\left(\frac{w^2}{\cos\left(w\right)}-1\right)$$

$$\lim_{x,y\to0,0}\left(\frac{1-\cos\left(xy\right)}{x^2}\right)$$

$$\frac{dx}{x-x^2}=dy$$

$$\left(6x^2-10xy+2\right)\left(2z-xy+4\right)$$

$$\frac{d}{dx}\sqrt[3]{6x-9}$$

$$\left(-3xy^5\right)^2\:\left(x^3y\right)^{-1}$$