Given the three end points (3,8), (5,20/3) and (6,5) which are written in the form of (x1,y1), (x2,y2) and (x3,y3).
Write out the formula to obtain the equation of the parabola
Write out the given coordinates
Substitute the coordinates into the given equation above to obtain the three equations
Combining the three equations together
Hence, the three equations above are the equations of the parabola with three unknowns a,b and c.