Vertical Line Test tests if a function is actually a function. How’re you gonna have 2 outputs for the same input.
Horizontal Line Test tests if a function is invertible.
First Derivative Test:
Tests if something is a critical point. (Or just gets you the slope - whatever way of thinking you prefer.)
Conditions
If or , then it’s a critical point.
Second Derivative Test:
Tests if a critical point a local max or minimum.
Conditions
If:
- , local max
- , local min
- , inconclusive
A related concept is the Point of Inflection!