$$a-b^2=a^2-b^2+ab$$

$$\lim_{n\to\infty}\left(\frac{n+2\sqrt{n}}{n^2}\right)$$

$$\left(7x^2-15\right)\left(7x^2+9\right)$$

$$y=\cos\left(x^{2}\right)\cdot\ln\left(x^{2}\right)$$

$$\int\left(\frac{2x+21}{2x^2+9x+-5}\right)dx$$

$$\frac{dy}{dx}=\frac{y\left(x\right)}{x-2y\left(x\right)}$$