1. The problem statement, all variables and given/known data I want to know how to find equation for the interpolated function of any degree. On Mathematica, for example. 3. The attempt at a solution Unfortunately, on Excel, the plots are deceiving because the points on the plot are actually out of range. For example, this equation: - 0.037*Math.pow(i,5) + 0.857*Math.pow(i,4) - 8.406*Math.pow(i,3) + 32.33*Math.pow(i,2) - 46.68*i + 260.2 is displayed to be in the range of 0 and 255 between values 1 and 21 for i. however, when plugging in numbers, values are clearly not in the range. you get a negative number for i =18. So therefore, is there a more accurate way of finding regression curves for data AND the equation for the curve?