Points
Test the following data table to see whether the data are quadratic.
able[[x,-3,-2,-1,0,1],[y,-1,-4,-5,-4,-1]]
Calculate the first-order and second-order differences.
able[[x,y,First-order difference,Second-order difference],[-3,-1,x,],[-2,-4,,],[-1,-5,,],[0,-4,,],[1,-1,,]]
This data is because the Second-order difference is equal to and the same all the time.