The Fit Line option finds the parameters 
and 
for the straight line that fits the points to minimize the residual sum of squares. The model for the ith row is written 
.
and for the straight line that fits the points to minimize the residual sum of squares. The model for the ith row is written .A polynomial of degree 2 is a parabola; a polynomial of degree 3 is a cubic curve. For degree k, the model for the ith observation is as follows:
