Consider 3 points with coordinates (0; 1), (1; 0) and (2; 3). Find a parabola passing through these points. First, substitute the coordinates in the parabola equation y = ax^{2}+bx+c and solve the set of equations 1=c, 0=a+b+c, 3=4a+2b+c. The solution is a = 2, b = 3, c = 1. Thus y = 2x^{2}  3x + 1. The parabola vertex is (b/2a; f(b/2a)) = (3/4; 1/8). a = 2 then the branches of the parabola are updirected. The model is a movie. To navigate through the movie use Play, Pause, Stop, Previous step and Next step buttons.
