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I have the following equation:

Solve[1000 Sqrt[2] == (702.762 S^2)/(
0.5[1 + 930.132/S^2 + 0.5[-0.2 + 30.4981 Sqrt[1/S^2]]] + 
Sqrt[-(930.132/S^2) + 
0.5[1 + 930.132/S^2 + 0.5[-0.2 + 30.4981 Sqrt[1/S^2]]]^2]), S]

but it doesn't work. "Solve was unable to solve the system with inexact coefficients or the \ system obtained by direct rationalization of inexact numbers present \ in the system. Since many of the methods used by Solve require exact \ input, providing Solve with an exact version of the system may help" How ca

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closed as off-topic by Daniel Lichtblau, Coolwater, m_goldberg, Henrik Schumacher, Michael E2 Feb 8 '18 at 3:21

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – Daniel Lichtblau, Coolwater, m_goldberg, Henrik Schumacher, Michael E2
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 3
    $\begingroup$ Focus on: 0.5[1 + 930.132/S^2 + 0.5[-0.2 + 30.4981 Sqrt[1/S^2]]]. [] is used specifically for function calls in Mathematica. If you're intending to multiply these values, make sure to use () instead. $\endgroup$ – eyorble Feb 7 '18 at 10:06
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    $\begingroup$ And never use an upper-case letter to start a variable name, as it may conflict with internal Mathematica names. $\endgroup$ – David G. Stork Feb 7 '18 at 10:14
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Numerical solve is the method you need:

NSolve[0 == -1000 Sqrt[2] + (702.762 S^2)/(0.5 (1 + 930.132/S^2 +0.5 (-0.2 + 30.4981 Sqrt[1/S^2])) +Sqrt[-(930.132/S^2) +0.5 (1 + 930.132/S^2 + 0.5 (-0.2 +30.4981 Sqrt[1/S^2]))^2]), S]
(* {{S -> -7.12064}, {S -> 7.12064}} *)
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  • $\begingroup$ Furthermore, I want to use the positive value of this solution as a coefficient of another equation. How can I do this? $\endgroup$ – Gae P Feb 7 '18 at 10:47
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    $\begingroup$ Just take the second part([[2]]) of the NSolve-result or give a constraint inside NSOlve NSolve[{0 == -1000 Sqrt[2] + (702.762 S^2)/(0.5 (1 + 930.132/S^2 +0.5 (-0.2 + 30.4981 Sqrt[1/S^2])) +Sqrt[-(930.132/S^2) +0.5 (1 + 930.132/S^2 + 0.5 (-0.2 +30.4981 Sqrt[1/S^2]))^2]),S>0}, S] $\endgroup$ – Ulrich Neumann Feb 7 '18 at 11:15

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