y

A1(x) = x
A2: 2
A3: 3
A4: 5
A5: 6
A6: 8
A7: 9
A8: 11
B2: 4
B3: 6
B4: 7
B5: 9
B6: 12
B7: 14
B8: 15
ResidualPlot({(2, 4), (3, 6), (5, 7), (6, 9), (8, 12), (9, 14), (11, 15)}, FitPoly[{(2, 4), (3, 6), (5, 7), (6, 9), (8, 12), (9, 14), (11, 15)}, 1])