$$a^{2}+4\sqrt{15}a-45=o$$
$a=\sqrt{o+105}-2\sqrt{15}$
$a=-\sqrt{o+105}-2\sqrt{15}$
$a=\sqrt{o+105}-2\sqrt{15}$
$a=-\sqrt{o+105}-2\sqrt{15}\text{, }o\geq -105$
$o=a^{2}+4\sqrt{15}a-45$
