$\lim_{x\to\frac{\pi}{4}}\left(\frac{\sec\left(2x\right)}{1-\tan\left(x\right)}\right)$

$\frac{15x}{9}=5$

$\cos2v-\sin4v$

$\left(x-700\right)\left(x-800\right)$

$\frac{\sqrt{36x^4}y^{-1\:3\sqrt{\left(x^2y\right)^2}}}{3\sqrt{27x^9y}}$

$3x^2=108$

$\frac{dp}{dx}=p^3+4p$