$$4k^2-\frac{3k^4}{7k^2}$$

$$a^2-3a+6$$

$$4-p-2x+3p-7x$$

$$2\sin\left(x\right)\cdot\cos\left(x\right)=6\sin^3\left(x\right)$$

$$\frac{dy}{dx}x+4x=0$$

$$\csc\left(x\right)-\sin\left(x\right)=\frac{\cos^2x}{\sin\left(x\right)}$$

$$x\frac{dy}{dx}=x^3+3y$$