$factor\left(x^4-5x^2+4\right)$

$factor\left(x^2-36\right)$

$\frac{sec\left(t\right)-cos\left(t\right)}{sin\left(t\right)}$

$4\left(x+2\right)-3\left(x-5\right)$

$\left(x+2\right)\left(x+3\right)$

$\left(2+\sqrt{y}\right)\left(2-\sqrt{y}\right)$