economics

    Q = AL3 + BL2, where Q is output rate and L is labor input.

Why it has to be a cubic function? Why there is no constant (intercept) in the function? Please explain briefly in your own words. 

2. Is the online retail (e.g. Amazon.com) qualified as a perfectly competitive market by the four market characters listed in the lecture note? If not, which character(s) is (are) not qualified? Please discuss it briefly.