[MATHEDCC] Growth Rate and Growth Factor

SYRILDA MILLER (SYMILLER@ECLIPSE.NET)
Sun, 12 Apr 1998 21:56:38 -0400

I am writing notes to teach a unit comparing linear functions to
exponential functions. I have defined the growth rate for a linear
function to be either the change in y when x changes by one unit or the
change in y divided by the change in x. With a linear function the
growth rate is a constant which can be seen in a linear equation as the
slope.

My question is about vocabulary for the corresponding characteristic
with exponential functions. For
y = 3(1.2)^x I would say that there is a "growth factor" of 1.2,
meaning that when x increases by 1 then the value of y is
correspondingly multiplied by 1.2 (thereby making sense of using the
word "factor" in the terminology)

Using a table of values, the growth factor is the ratio of new value
of y divided by original value of y when x changes by one. Is this use
of the term "growth factor" common and acceptable? ( I have seen the
idea of saying there is a 20% growth rate, but want to avoid that
terminologyl. I feel it would be confusing now that I have used growth
rate as I have for the linear functions.)

My purpose is to contrast "growth rate" for linear functions with
"growth factor" for exponential functions. Any opinions?
This is a pre-calculus class.

Syrilda Miller
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