$3abx^2+2y^2+2x^2+3aby^2$

$4ab\:+\:\frac{3a}{a}$

$1-\frac{sen^2}{sec^2}=cos^4$

$\frac{x^4+18x^2+81}{x-1}$

$\frac{sen^2x\:\left(1-cos\:x\right)}{\left(1-cos\:x\right)\left(1-cosx\right)}$

$\frac{1}{\sin\left(a\right)\cos\left(a\right)}=\csc\left(a\right)\sec\left(a\right)$

$\int\frac{1}{x\left(\sqrt{x}+1\right)}dx$