Answer
... $>0$ ...
and
... $<0$
(in that order)
Work Step by Step
Exponential growth and decay models are given by $A=A_{0}e^{kt}$
in which $t$ represents time,
$A_{0}$ is the amount present at $t=0$, and
$A$ is the amount present at time $t$.
If $k>0$, the model describes growth and $k$ is the growth rate.
If $k<0$, the model describes decay and $k$ is the decay rate.
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So, the blanks should be filled in with
... $>0$ ...
and
... $<0$
(in order)
