# Mathematica: Solve error

• Mathematica

## Main Question or Discussion Point

Here is my code
Code:
Nl = 10^(49) ;
Nh = 100 ;
b = 4*10^(-13) ;
Rs = N[((3 Nl)/(4 Pi b Nh^2))^(1/3)];
a = 6*10^(-18) ;

Solve[x/(4 Pi r^2)  E^(-Nh a x) a Nl == (1 - x)^2 b Nh,
x]

When I run it, it shows the error:
"Solve::nsmet: This system cannot be solved with the methods available to Solve. >>"

How can I solve this equation? Thanks.

Last edited:

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Since you have an undetermined parameter, Mathematica tries to find an analytic solution, which I don't think will work in this case. If you know the value of r, then a numerical solution is possible (assuming x is a real number).

Since you have an undetermined parameter, Mathematica tries to find an analytic solution, which I don't think will work in this case. If you know the value of r, then a numerical solution is possible (assuming x is a real number).
Thanks for your reply. Do you know any way to plot this (x vs. r) in mathematica? x should be some value between 0 and 1, and r is a positive number.

Thanks for your reply. Do you know any way to plot this (x vs. r) in mathematica? x should be some value between 0 and 1, and r is a positive number.
The Plot3D command should be useful.