$$\left(m+n+p\right)\left(m-n-p\left\{\right\}\right)$$

$$-\frac{20}{5-4}$$

$$\frac{9}{0}$$

$$\frac{d^2y}{dx^2}=-5\frac{dy}{dx}+14y$$

$$\frac{\cos a-\sin^3a+\sin a}{\sin a}=\cot a-\cos^2a$$

$$\frac{d^5y}{dx^5}=0$$