$$\lim_{x\to4}\left(\frac{2x^2-8x}{x^2-16}\right)$$

$$7\sqrt{20}$$

$$\frac{2}{3}\cdot\frac{3}{2}\cdot3y$$

$$\lim_{x\to0}\left(9\sin x\right)^{8\tan\left(x\right)}$$

$$3ax-3x+4y-4ay$$

$$2x+2y-3z=1$$

$$ln\left|sin\left(x\right)\right|-ln\left|cos\left(x\right)\right|$$