$\tan\left(23\right)\frac{85}{9.5}$

$-\:4\:\left(\:4\:-\:5\:+\:2\:\right)\:-\:3\:-\:\:\left\{1\:-\:\left[\:6\:+\:\left(\:-\:3\:-\:1\:\right)\:-\:\left(\:-\:2\:+\:4\:\right)\:\right]\:+\:3\:-\:4\:\right\}$

$-5x^2+4x^2$

$\lim_{x\to\infty}\left(\frac{9x^3}{e^{7x}}\right)$

$\sqrt{\frac{\sin\left(x\right)-1}{\sec\left(x\right)-1}}$

$y'+5y=e^x$

$\sqrt[20]{\sqrt[4]{\left(-2\right)}}$