$\:-7x^3-x-2y^3+3y^3-x^3+3y^3-3x$

$cos\left(x+y\right)cos\left(x-y\right)=cos^{\left(2\right)}\left(x\right)-sin^{\left(2\right)}\left(y\right)$

$\sec^2\left(a\right)+\csc^2\left(a\right)=\sec^2\left(a\right)\csc^2\left(a\right)$

$3\left(x+5\right)+6=5+5\left(x+2\right)$

$4\left(x+5\right)-6x$

$\left(-8a^2\right)\left(-6a^3b^2+5a^2b^3-3\right)$

$8\sqrt{2}\cos\left(x\right)+6=-2$