Solve the first order hyperbolic equation

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SUMMARY

The discussion focuses on solving the first order hyperbolic equation 3 du/dx + 2x du/dt = 2u with the initial condition u(x,0) = 2x + 4. The method of characteristics is employed, leading to characteristic equations dx/ds = 3, dt/ds = 2x, and du/ds = 2u. Participants confirm the integration of du/dx = 2u/3 and derive the solution involving logarithmic expressions, ultimately expressing r in terms of t and x as r = ±√(x² - 3t).

PREREQUISITES
  • Understanding of first order hyperbolic equations
  • Familiarity with the method of characteristics
  • Knowledge of differential equations and integration techniques
  • Ability to manipulate logarithmic functions and initial conditions
NEXT STEPS
  • Study the method of characteristics in greater detail
  • Learn how to solve first order differential equations using separation of variables
  • Explore the implications of initial conditions on the solutions of hyperbolic equations
  • Investigate the behavior of solutions as x approaches large values
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Mathematicians, physics students, and engineers interested in solving hyperbolic partial differential equations and applying the method of characteristics in practical scenarios.

  • #31
Plug it in and see what sign causes you trouble (I think it'll be the - sign that will be the troublesome one). Look for large values of x to find the right sign. Then you're done, you've got the right solution!
 
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  • #32
Which equation shall I plug the r value into?

Is it:

log u = x2/3 + log (2r+4) - r2/3
 
  • #33
Yes.
 

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