Financial analysts use graphical models to predict stock values for a new stock. It is important for stock brokers to know about instantaneous changes of a stock price. To create a stock pricing model, analysts look at past behavior and future expectations for that stock.

A stock broker has developed the following model for the price of his favourite stock:

22 + + , < 0 () = {, = 0

3( + 1)4 + , > 0

the question:Why is it important for the stock broker to know about the instantaneous changes of a stock price?