Answer
The domain is all real numbers except $x\ne\frac{1}{3}$.
Work Step by Step
Any restriction on the domain occurs when any value of $x$ results in an undefined fraction. To determine what value of $x$ will result in a $0$ (creating an undefined fraction), place the expression in the denominator equal to zero:
$3x-1=0$ and solve.
$3x=1$
$x=\frac{1}{3}$
Thus, $x\ne\frac{1}{3}$ is the restriction for the domain.
