$18.81\left(12.6+3.2\right)$

$y^4+2y^2+y=0$

$\left(121-x^2\right)\left(11-x\right)$

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

$\left(\frac{x^{4a}}{5}+\frac{\left(b^4x\:y^{\left(a+1\right)}\right)}{4}\right)^2$

$2\cos\left(a\right)\sec\left(a\right)-\tan\left(a\right)\cot\left(a\right)=1$

$\lim_{n\to0}\left(xlnx\right)$