$\lim\:_{\delta\:\:x\to\:0}\frac{\left(x+\delta\:\:x\right)^2-x^2}{\delta\:\:x}$

$\frac{dy}{dx}+7y-4e^{-5x}=0$

$\left(\frac{5}{4}x\right)\left(-\frac{1}{3}\right)$

$\frac{dy}{dx}\left[\frac{tan\left(7x\right)\sqrt{x+2}}{\left(x^2+7\right)^7}\right]$

$\lim_{x\to\infty}\left(\frac{x^3+e^x}{6x^3+4x}\right)$

$x^2+x-72<0$

$16x^2x+48yx+36y^2$