$$8c^2-14c-15$$

$$\left(6m^3-7n^4\right)^2$$

$$2z^2-7z-4$$

$$\frac{d}{dx}\left(\frac{x^3+3\sqrt{x}}{x}\right)$$

$$\frac{senxcosx}{tanx}=2$$

$$14x\frac{dy}{dx}=x^{-1}$$

$$\frac{dy}{dx}=\frac{\left(-2xy-x\right)}{e^{x^2}}$$