Answer
$\log(3x)$
Work Step by Step
Use the fact that $\log a^b=b\log a$ and $(a^b)^n=a^{bn}$ to simplify. $$2\log \sqrt{x}=2 \log x^{\frac{1}{2}}=\log {(x^\frac{1}{2}})^2=\log(x)$$ Finally, use the fact that $\log(ab)=\log(a)+\log(b)$ to simplify the expression to $$\log x + \log 3 = \log(3x)$$
