Whist34 wrote:1) It seems like many sites regard growth as an increase in y instead of an increase in the rate of change. Does y have to increase for there to be exponential growth? Alternatively does y have to decrease for there to be exponential decay?
As far as I know, "growth" means "getting bigger" while "getting smaller" is called "decay" (or at least "negative growth").
Whist34 wrote:2) Should a be limited to a > 0 by definition for growth and decay?
As far as I know, "a" can be any non-zero value (a = 0 would be pretty dull!), but, for "real life" stuff, positive is what makes sense. So it's more of a word-problem thing than a math thing.
Whist34 wrote:3) If I am wrong and exponential growth is indeed as x increases so does y, then would y = -3(0.5)x be growth and y = -3(1.2)x be decay?
I think the "growth" and "decay" thing is more related to the exponential part, bx
, and whether it is getting larger or getting closer to zero.