Steps To find the line of best fit for N points:
Step 1: For each (x,y) point calculate x2 and xy
Step 2: Sum all x, y, x2 and xy, which gives us Σx, Σy, Σx2 and Σxy (Σ means "sum up")
Step 3: Calculate Slope m:
m = (N Σ(xy) − Σx Σy)/(N Σ(x**2) − (Σx)**2)) (N is the number of points.)
Step 4: Calculate Intercept b:
b = Σy − m Σx/N
Step 5: Assemble the equation of a line
y = mx + b
Done!
Second is the polyfit function method from the numpy library!