I know it is not something easy to crack. I spent close to 6 months on how to plot those Polynomials...
It is pure mathematics...
I will share a sample in the coming days.
Before we go further, some amount of minimum Polynomials...
Q: Why do we need polynomials of higher degree ?
A: We think with more degree, prediction will be better.
Q: How does a Degree 1 equation look like ?
A: aX+c. a and C are constants and X is the variable... If for Example 3X + 1 is the equation then you will get 4, 7, 10 as the values...
Q: How does a Degree 2 equation look like ?
A: aX^2+ bX + c. a, b, c are constants and X is the variable...
Degree 3 : aX^3 + bX^2 + cX + d
Degree 4 : aX^4 + bX^3 + cX^2 + dX + e
So for a given set of Values if you can deduce the Constants a, b, c, d etc... then you can predict the Values for a given X....
Most of the time,
A degree 1 polynomial will be straight line
A degree 2 polynomial might have two lines / curves
A degree 3 polynomial might have three lines / curves and so on ...
Please do some googling and understand what I said above... Otherwise even with the sample that I would be sharing you will not understand anything...
Please have a look at
https://newtonexcelbach.wordpress.com/2011/01/19/using-linest-for-non-linear-curve-fitting/
http://chandoo.org/wp/2011/01/26/trendlines-and-forecasting-in-excel-part-2/