Answer
fill the blanks with
$b^{x}$
... $(-\infty, \infty)$
... $(0, \infty)$
Work Step by Step
Book references:
Definition of the Exponential Function
(just below Figure 4.1)
and
Characteristics of Exponential Functions of the Form $f(x)=b^{x}$
(below Figure 4.4)
The exponential function with base $b$ is defined by $f(x)=b^{x},\ b>0$ and $b\neq 1$.
The domain is: all real numbers x.
An image with examples for both cases , $b>1$ and $0
