$$4\left(x-2y+3z\right)$$

$$\int\frac{sec^2x}{tanx\left(tanx+1\right)}dx$$

$$\frac{d}{dx}8t^{\sqrt{t}}$$

$$\frac{dz}{dx}=\frac{1}{x^2}-\frac{2z}{x}$$

$$5x\:-\:2\left(15\:-\:x\right)$$

$$\left(4y\:+\:9x\right)\:\left(4y\:-\:9x\right)$$

$$\left(x-5\right)\left(xy'\:+3y\right)=2$$