$\lim_{x\to0}\left(\frac{a}{x+dx}\right)$

$\frac{dy}{dx}=\frac{x+2}{y^4}$

$\lim_{x\to0}\left(\frac{4x}{4x+\sqrt{16x^2+x}}\right)$

$\frac{-6x-5}{3}<\frac{4x-4}{2}$

$\int_{\frac{\pi}{-4}}^{\frac{\pi}{6}}\left(-\sec\left(x\right)\tan\left(x\right)\right)dx$

$121c^{\left(4\right)}\:+\:66c^{\left(4\right)}\:+\:9$

$cot\left(x\right)\left(sec^2\left(x\right)-1\right)=tan\left(x\right)$