Answer
$4 + \log{x}$
Work Step by Step
RECALL:
The product rule for logarithms:
$\log{bc} = \log{b} + \log{c}$
Use the product rule to obtain:
$\log{(10,000x)}
\\= \log{(10,000 \cdot x)}
\\= \log{10,000} + \log{x}
\\=\log{10^4} + \log{x}$
Note that for all real numbers within its domain $\log{10^n}=n$.
This means that $\log{10^4} =4$.
Thus,
$\log{10^4} + \log{x}= 4 + \log{x}$