$\left(3a^4+9a^8\right)\left(3a^4-7a^8\right)$

$a^2-\:10a\:+\:25\:=0$

$\frac{1}{\cos\left(x\right)}-\frac{\cos\left(x\right)}{1+\sin\left(x\right)}=\tan\left(x\right)z$

$\tan\left(\frac{x}{2}\right)=\frac{\tan\left(x\right)}{\sec\left(x\right)+1}$

$\frac{-2h^2+h}{\left(h^2+1\right)\left(h\right)}$

$\left(\frac{3x}{5}+1\right)=4$

$4r^2-25$