In details

Coordinates of the parable vertex

When a> 0, the parable has an upward concavity and a minimum point V; when <0, the parable has downward concavity and a maximum point V.

In any case, the coordinates of V are . See the graphics:


The image set Im of the function y = ax2 + bx + c, a 0 is the set of values ​​y can assume. There are two possibilities:

1st - when a> 0,

a> 0

2nd when a <0,

a <0

Next: Parable Construction