$\lim_{x\to\infty}\left(\frac{x}{25\left(25+x^2\right)^{\frac{1}{2}}}\right)$

$\left(11axz^2y^2+w^4\right)\left(11axz^2v^2-w^4\right)$

$\lim_{x\to0}\left(\frac{4x}{tanx}-cosx\right)$

$\lim_{x\to\infty}\left(\frac{x^2-3}{e^x}\right)$

$\frac{d}{dx}\left(\frac{\left(y+6\right)}{\left(6y^2+x\right)}\right)$

$u'=\frac{xsix\left(x\right)}{u-x}+1$

$1-2x\le0$