Lời giải:
\( \Delta: y = \frac{2}{(x_0 + 1)^2}(x - x_0) + \frac{2x_0}{x_0 + 1} \)
\( S_{OAB} = \frac{1}{2} \times OA \times OB = \frac{1}{2} \times \left|-x_0^2\right| \times \left|\frac{2x_0^2}{(x_0 + 1)^2}\right| = \frac{1}{4} \)
\(\Leftrightarrow \left|\frac{x_0^4}{(x_0 + 1)^2}\right| = \frac{1}{4} \)
\(\Leftrightarrow \left|\frac{x_0^2}{x_0 + 1}\right| = \frac{1}{2} \)
\(\Leftrightarrow \begin{cases}
2x_0^2+ x_0 +1 = 0 \quad \text{(vô nghiệm)} \\
2x_0^2 - x_0 - 1 = 0
\end{cases} \)
\( \Leftrightarrow x_0 = 1 \text{ hoặc } x_0 = -\frac{1}{2} \)
Vậy \( M\left(-\frac{1}{2}, -2\right) \) hoặc \( M(1, 1) \).