The given equation is:
\[
\frac{1}{x} - \frac{1}{x - 2} = 3.
\]
Step 1:
Find the LHS with a common denominator. The common denominator is \( x(x - 2) \), so we rewrite the left-hand side:
\[
\frac{1}{x} - \frac{1}{x - 2} = \frac{(x - 2) - x}{x(x - 2)} = \frac{-2}{x(x - 2)}.
\]
Thus, the equation becomes:
\[
\frac{-2}{x(x - 2)} = 3.
\]
Step 2:
Multiply both sides by \( x(x - 2) \) to eliminate the denominator:
\[
-2 = 3x(x - 2).
\]
Step 3:
Expand the right-hand side:
\[
-2 = 3x^2 - 6x.
\]
Step 4:
Move all terms to one side of the equation:
\[
3x^2 - 6x + 2 = 0.
\]
Step 5:
Solve this quadratic equation using the quadratic formula:
\[
x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a},
\]
where \( a = 3 \), \( b = -6 \), and \( c = 2 \).
Substitute the values:
\[
x = \frac{-(-6) \pm \sqrt{(-6)^2 - 4(3)(2)}}{2(3)} = \frac{6 \pm \sqrt{36 - 24}}{6} = \frac{6 \pm \sqrt{12}}{6}.
\]
Simplify \( \sqrt{12} \):
\[
x = \frac{6 \pm 2\sqrt{3}}{6} = 1 \pm \frac{\sqrt{3}}{3}.
\]
Thus, the two possible values of \( x \) are:
\[
x = 1 + \frac{\sqrt{3}}{3} \quad \text{or} \quad x = 1 - \frac{\sqrt{3}}{3}.
\]
Conclusion:
The solutions are \( x = 1 + \frac{\sqrt{3}}{3} \) and \( x = 1 - \frac{\sqrt{3}}{3} \).