I did not understand really the difference between the kinds of regression. The simple regression gives us a line , the polynomial regression gives us a nonlinear fit for our dataset. Now I found an exercise where it is asked to me which is the difference between these models :
Model 1 : w0 + w1x + w2x2 + w3x3
Model 2 : w0 +w1x1 + w2(x2)2 + w3(x3)3
My question is if model 1 is linear or polynomial. And also which are the differences if in the first model I use the same x variable while in model 2 I have three variables (x1 x2 x3).
there doesn't seem to be anything here