We began graphing exponential decay functions of the form y=ab^x, where a>0 and 0<b<1. In other words, b is a fraction. We graphed them the same way we graphed exponential growth, by letting x=0 and x=1. When x=0, y=a, so the y intercept is (0,a). Then you compute the y value for x=1. Alexa was able to identify if functions were growth or decay by looking at their equations and examining the b value. She completed exercises 3-8 on p. 489.