Parabolas wrapped in equation

y = a(x-h)^2 + k 

If there's a parabola. You can find and tweak it with these parameters
'a' defines whether parabola is facing upward of downward
'h' defines horizontal position of the vertex of parabola. 
'k' defines the narrowness of parabola. 

A vertex of a parabola is the maximum or the minimum of the parabola.