Recall in Section $1\mathrm{.}5$:

For exponential function f$($x$)=$abx, percent change can be obtained by calculating $($b$1)100\%($or$,$ equivalently, b$=1+$r$).$

$$

While now in Section $2\mathrm{.}1$:

Given f$($x$)=350280(\mathrm{.}992$x$),$ percent change obtained by calculating f$($x$2)$f$($x$1)$f$($x$1)100\%=$new$$oldold$100\%.$

$$

Note that:

We can NOT use $($b$1)100\%$ for calculating percent change in f$($x$)=350280(\mathrm{.}992$x$)$ because $[$ Select $]["$this f$($x$)$ is not in the ab$^$x form", "math says so$"].$

$$

Conclusion for calculating percent change:

f$($x$2)$f$($x$1)$f$($x$1)100\%$ is a general form of percent change that works $[$ Select $]["$for any type of functions", "only for functions in the form of f$($x$)=$ab$^$x$"]$ over $[$ Select $]["1$ unit time period", "any time period"$],$ while$$

$($b$1)100\%$ is a specific form of percent change that works $[$ Select $]["$only for functions in the form of f$($x$)=$ab$^$x$",$ "for any type of functions"$]$ over $[$ Select $]["1$ unit time period", "any time period"$].$