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You mean [tex]\dfrac{x-3}{2x-1}[/tex], right?
So to find excluded value, you just set denominator equal to zero;
[tex]2x-1 = 0[/tex]
From here, you just solve for x. Add both sides by 1 then divide both sides by 2, then you would have final answer;
[tex]\boxed{x=\dfrac{1}{2}}[/tex]
So [tex] \frac{1}{2} [/tex] is your excluded value.
