# Solving two equations with modified Bessel functions

I am trying to solve two equations with Bessel functions in them,

1) C1*BesselK[0, 3.7268*10^-4*x] == 1.3*10^-6

2) x == 53.66*C1*BesselK[1, 3.7268*10^-4*x]

here x and C1 are unknown constants.

I have tried to solve it with the following expression, but to no use.

Solve[{C1*BesselK[0, 3.7268*10^-4*x] == 1.3*10^-6,
x == 53.66*C1*BesselK[1, 3.7268*10^-4*x]}, {C1, x}]


Any suggestions are more than welcome. Regards

• Thinga like your 3.7268e4 are not the Mma notation. Use == instead of = in equations. Could you kindly edit your question to pass to the Mma notations, such that one is able to copy-paste it in his notebook? – Alexei Boulbitch May 11 '16 at 11:17
• Thanks Alexei for your response I have changed it – Gul May 11 '16 at 11:33

## 1 Answer

Your equation is too complicated for Solve. You can however try NSolve with a range for x. I choose here 0<x<1.

NSolve[{C1*BesselK[0, 3.7268*10^-4*x] == 1.3*10^-6,
x == 53.66*C1*BesselK[1, 3.7268*10^-4*x], 0 < x < 1}, {C1, x}]


{{C1 -> 1.30002*10^-7, x -> 0.136815}}