$\left(81r\right)^{\frac{1}{4}}$

$\frac{1+2tan\left(2\right)}{sec\left(2\right)}$

$\lim_{x\to0}\:\frac{ln\left(cos4x\right)}{2x^2}$

$\frac{1}{8}\left(x-5\right)=\frac{1}{9}\left(x-4\right)$

$\left(2n\:+1\right)x^2\:-\:5n\:x\:+\:20\:=\:0$

$\frac{x^2+2ax+a^2}{mx+ma}$

$\int\:\frac{x^2-3}{\left(x^2+1\right)^2}dx$