$\frac{d}{dx}\:7\:sen\:x$

$4csc^{\left(2\right)}2x+4csc^{\left(2\right)}2xcot^{\left(2\right)}2x$

$\lim_{x\to1}\left(\frac{n^2+3}{3n^2-1}\right)$

$\left(\sqrt{x-7}\right)^6$

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

$\frac{6.9}{3}$

$\left(3x^3+x^2-1\right)+3\left(-x^3+x^2+5\right)$