if you had
ax^2+bx+c
a is the leading term
when a>0, the parabola opens up and therfor has a minimum point and no max since it goes up infinitely
when a<0, the parabola opens down and therefor has a maximum point and not min since it goes down infinitely
-x^2+8x+9
-1<0
opens down
has max
vertex=max
