$\left(\frac{3}{5}x^3yz+\frac{1}{5}xyz+\frac{1}{3}x^2y^2+\frac{2}{3}z^2\right).\left(\frac{15}{2}yz^2tx\right)$

$35:-5$

$\int6^{-x+3}dx$

$x\:+\:-7\:=\:18$

$sin4t=2sin2tcos2t$

$\frac{d}{dx}\cos^2\left(3x+1\right)-\sin^2\left(3x+1\right)$

$\lim_{x\to\infty}\left(x^3-x\right)$