Answer
a. $f(5)=10.75$
b. $x=-10.4$
c. Domain:- $(-\infty,\infty)$. Range:- $(-\infty,\infty)$.
Work Step by Step
The given function is
$f(x)=1.25x+4.5$
a.
Substitute $x=5$ into the function.
$\Rightarrow f(5)=1.25(5)+4.5$
Clear the parentheses.
$\Rightarrow f(5)=6.25+4.5$
Subtract.
$\Rightarrow f(5)=10.75$.
b.
Substitute $f(x)=-8.5$ into the function.
$\Rightarrow -8.5=1.25x+4.5$
Subtract $4.5$ from both sides.
$\Rightarrow -8.5-4.5=1.25x+4.5-4.5$
Simplify.
$\Rightarrow -13=1.25x$
Divide both sides by $1.25$.
$\Rightarrow \frac{-13}{1.25}=\frac{1.25x}{1.25}$
Simplify.
$\Rightarrow -10.4=x$.
c.
This is a linear function.
Hence, all real number inputs will result in real number outputs.
The domain is $(-\infty,\infty)$.
and the range is $(-\infty,\infty)$.
