$2\cdot13+2\left(-13\right)$

$10x+10+20+2x+2x+2x$

$y^2z^4\cdot4y^3z^6\cdot2yz^3$

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

$\sin\left(4t\right)=4\sin\left(t\right)cos^3\left(t\right)-4\sin^3\left(t\right)\cos\left(t\right)$

$\csc\left(-x\right)=-\frac{5}{4}$

$\lim_{x\to5}\left(\frac{sin\left(x-5\right)}{\left(x-5\right)^{3\:}}\right)$