$\frac{cos\left(a+b\right)}{sin\left(a\right)cos\left(b\right)}=cot\left(a\right)-tan\left(b\right)$

$4\:-\:3\left(5\:+\:\left(3\:-\:5\right)^2\:-\:\left(2\:-\:5\right)^3\:+\:\left(\sqrt{64}-\sqrt{25}\right)\right)$

$9x^24-30x^2y+25x^2y^2$

$\lim_{x\to3}\left(\frac{x^2-25}{5-4x-x^2}\right)$

$6\left(-7\right)+\left(-9\right)\cdot12-4\left(-8\right)$

$-5\left(-3\right)\left(-5\right)$

$\int\frac{x^7}{\sqrt[3]{x^2+1}}dx$