$\cos3\left(a\right)=\cos\left(a\right)\left(1-2\sin\left(a\right)\right)\left(1+2\sin\left(a\right)\right)$

$\frac{\left(2^n\right)x^n}{\sqrt{\left(4n+1\right)\cdot\:5^n}}$

$x^2+24x+80$

$2\sin\left(\theta\right)=-\sqrt{3}$

$\frac{a-b}{a^2}\cdot2a$

$-3y+1-2y$

$\frac{3a}{\sqrt{2}+\sqrt{x}}$