玩玩

血狼王

来源：artofproblemsolving.com/community/c6h2363756_i_get_it173

设$c$ 为一复数。求最小的正数$q$，使得对一切满足$$|c^2+qc+1|\le 1$$的$c$，均有$$|c|\le q$$成立。

hbghlyj

设$c^2+qc+1=(c-z_1)(c-z_2)$, 则$\abs{c^2+qc+1}\le1\iff\abs{c-z_1}\cdot\abs{c-z_2}\le1$ Cassini oval