Example 3. Find the range of $y=\frac{3 x-1}{3 x-2}$.

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Example 3. Find the range of $y=\frac{3 x-1}{3 x-2}$.
Solve: From $y=\frac{3 x-1}{3 x-2}$ we get $x=\frac{2 y-1}{3 y-3}$.
To make $x$ meaningful, it is necessary that $3 y-3 \neq 0$, i.e., $y \neq 1$.
Therefore, the range of the function is all real numbers except $y \neq 1$.
Four, Using a quadratic function to find the range
If $y=a x^{2}+b x+c \quad(a \neq 0)$, then the range is
When $a>0$, $y \geqslant \frac{4 a c-b^{2}}{4 a}$,
When $a<0$, $y \leqslant \frac{4 a c-b^{2}}{4 a}$.