y

A1(x) = x
A2: 2
A3: 4
A4: 5
A5: 6
A6: 8
A7: 9
A8: 11
B2: 4
B3: 5
B4: 8
B5: 11
B6: 22
B7: 33
B8: 67
ResidualPlot({(2, 4), (4, 5), (5, 8), (6, 11), (8, 22), (9, 33), (11, 67)}, FitGrowth[{(2, 4), (4, 5), (5, 8), (6, 11), (8, 22), (9, 33), (11, 67)}])