Since the denominators of the equation are (x-3) and (3-x) require that x≠3 is true, the solution x=0 is an effective solution.

Answers to supplementary questions:

(x- 1)/(x-2)= 1/(x-2)

The solution x- 1= 1, that is, x=2, but the denominator of the equation is (x-2), which requires x≠2, so the solution x=2 is invalid, that is, the equation has no solution.

3/(x+3)=5/(x+3)

Multiply both sides of the equation by (x+3): 3=5, and know that the equation has no solution.