D, Zeng Gen, you know, just make the denominator zero! Then you have to choose D.

The value range of x is X≥ 1/2. First of all, x cannot be equal to 0, and 2X- 1 must be greater than or equal to 0. Then we construct a set of linear inequalities, namely X≠0, 2X- 1≥0, and the solution set is the answer.

As for the last question, I don't understand what that m = _ _ 3 _ _ _ means. I'm sorry . .