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Reduce or Solve for symbolic equations? Both do not work for mine.

Posted 10 days ago
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I want to solve the followiwng system of equations:

enter image description here

Reduce[{u^e == 1 - u^f, Q == u^e  \!\(\*SubsuperscriptBox[\(N\),
\(t\), \(e\)]\) + u^f  \!\(\*SubsuperscriptBox[\(N\), \(t\), \(f\)]\),
\!\( \*SubsuperscriptBox[\(N\), \(t\), \(f\)] ==  \*FractionBox[\(
\*SubscriptBox[\(D\), \(t\)] -  \*SubscriptBox[\(P\), \(t\)] - Q\
\((\(-1\) - t + T)\)\  \*SubsuperscriptBox[\(\[Gamma]\[Sigma]\),
\(\[Epsilon]\), \(2\)]\),  SubsuperscriptBox[\(\[Gamma]\[Sigma]\),
\(\[Epsilon]\), \(2\)]]\),    Subscript[X,     t] ==
\[Theta]^t Subscript[X, 
0] + (1 - \[Theta]) Subscript[\[Lambda], t] \!\( \*UnderoverscriptBox[\(\[Sum]\), \(k = 0\), \(\(-1\) + t\)]\(
\(\*SuperscriptBox[\(\[Theta]\), \(k\)]\)[\(- \*SubscriptBox[\(P\),
\(\(-1\) - k + t\)]\) +  \*SubscriptBox[\(P\), \(\(-k\) + t\)]]\)\),
\!\( \*SubsuperscriptBox[\(N\), \(t\), \(e\)] ==  \*FractionBox[
SubscriptBox[\(X\), \(t\)],  SubsuperscriptBox[\(\[Gamma]\[Sigma]\),
\(\[Epsilon]\), \(2\)]]\)}, \ Subscript[P, t]]

Unfortunately, neither reduce nor solve work here. I get the error message: ". is not a quantified system of equations and inequalities." What does that mean?

If I write your equations like this

eqs = {ue == 1 - uf,
  Q == ue nte + uf ntf,
  ntf == (dmq - pt)/g,
  nte == xt/g}

and "forget" the xt - term (which is a complicated function of other (former?) pt's ) Reduce works giving lots of conditions.

Reduce[eqs, pt]

It is by no means clear what you want to do with your equations, which are really complicatedly written. You should avoid all these sub- and super-scripts

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