判別式 | Discriminant

影片內容：

00:05 – 甚麼是判別式? | what is discriminant?
04:11 – 判別式與圖像的關係 | relationship between discriminant and graph
05:09 – 例子 1 | example 1
05:43 – 例子 2 | example 2
06:34 – 例子 3 | example 3