A very simple equation: x!=\frac{(7!)!}{7!} It’s easy to find the solution: x = 7! - 1 = 5039 I used Mathematica to solve this equation: Solve[x! == (7!)!/7!, x] Reduce[x! == (7!)!/7!, x] No one of these functions gives the solution! Can someone comment this strange?

[image] Inverse Of Gamma Function? Questions Exact Inverse of (gamma function) = ? --------------> for example: Exact Inverse of (?x) = x²

Or this formula: floor(3/4+e^(1+ProductLog(-(1+log((2 ?)/x^2))/(2 e))))

Dear Mohamad, Thank you for your comments! But my question is more deep… Mathematica is aimed for different users, including children. Can you imagine their reactions when such a powerful system as Mathematica can’t solve a very simple problem? What are the real issues which don’t permit Mathemat…

You’re welcome. well, I think the Problem isn’t simple. we only write: solve(x!=a) but the problem is: there is not an standard mathematical formula to inverse of factorial function, you know. for example when we write: x!=a=>x=? and when we use (=) , we only want exact solution of problem but which…

It’s important to observe that Mathematica can treat such type of equation, e.g., Solve[x! == 7!/7, x] It gives the correct solution x = 6. As I understand the equation x! == (7!)!/7! may be reduced to equation x! == 5039! by simplifications, and then it may give the correct result. Why Mat…

Try this: Solve[(7!)!/(7!) == x!, x, Integers]

Thank you, Louis! For me is somewhat strange that if we do not specify that x is integer, then we do not obtain the result… The Set of Reals doesn’t contain the Set of Integers? What is the principle that governs the execution of Solve function?

Thank you, too. if you know which mathematical formula is used to solve x!=5039! please tell me. Regards

Factorial equations issues

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mhfard1370 (Mohamad Fard) July 9, 2016, 5:51am 2

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Factorial equations issues

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