$\frac{\left(x^2+2\right)}{\left(x^2-4\right)}$

$\frac{1}{senx}\cdot\frac{1}{senx}$

$-\int\left(\cos\left(x\right)\right)^2sin\left(x\right)dx$

$\sin\left(x\right)\left(\tan\left(x\right)+\cot\left(x\right)\right)=\tan\left(x\right)$

$\left(\frac{10x^4}{5x^6}\right)^3$

$\left(4st+5s^2t^3-st^3\right)\left(-5st+4s^2t-7st^3\right)$

$2x+3x-12x$