For the past couple of days I've been struggling to come up with a solution to this problem: I'm asked to write the output voltage \( {V_{0}} \) as function of the input voltages \( {V_{1}} \) and \( {V_{2}} \): \( {V_{0}}=f({V_{1},{V_{2}}}) \).

So far I've tried approaching the problem with the superposition principle as follows:

\( KCL) \) \( \frac{{V_{1}}-V^{-}}{{R_{1}}}=\frac{V^{-}-{V_{01}}}{{R_{2}}} \)

\( Given \) \( {V_{2}} = 0 \) \( then \) \( {V^{+}}=\frac{{R_{3}}}{{R_{3}}+{R_{4}}}{V_{0}}={V^{-}} \)

\( therefore \) \( \frac{{V_{1}}}{{R_{1}}}-\frac{{R_{3}}}{{R_{1}}}\frac{1}{{R_{3}}+{R_{4}}}{V_{0}}=\frac{{R_{3}}}{{R_{2}}}\frac{1}{{R_{3}}+{R_{4}}}{V_{0}}-\frac{{V_{01}}}{{R_{2}}} \)

But I'm not able to find a clean relationship between \( {V_{01}}\) and \( {V_{0}}\) so as to be able to write \( {V_{0}}=f({V_{1}}) \).

Then I would have done the same thing given \( {V_{1}} = 0 \) and added the two results together. Am I missing something?