Answer to question 1.1.14

[William Long]

I recently started using a print edition of the Early Transcendentals edition I ordered from Lulu, which I have enjoyed thus far. When I had a question about answer 1.1.14, I double-checked it in your online edition. The answer as given in both is 0.03x + 1.2, but it seems clear to me that the answer should be 0.03x + 4.2, since the sum of the costs of copies 1-20 (1.00 = 0.05 * 20) and copies 21-100 (3.20 = 0.04 * 80) is 4.20. Please advise.

Thank you,

W.L. Long

[William Long]

Ah, I think I now see my error with respect to finding "the equation... when x is more than 100." 

Since y=4.2 at x=100, I must subtract 100 from x before multiplying by 0.03:

    y = 0.03(x - 100) - 4.2 => y = 0.03x - 3.0 + 4.2 => y = 0.03x - 1.2

Regards,

W.L. Long