I can Plot these two functions written exactly this way and see intersection but Solve will not recognize the exponential expression. Please help me with feedback...

Solve[1/3Exp[-x/5]==Cos[x], x]

  • $\begingroup$ Restrict the (infinite) solution set, e.g. Solve[1/3 Exp[-x/5] == Cos[x] && 0 < x < 200 Pi, x] $\endgroup$ – ciao Sep 1 '20 at 22:32
  • $\begingroup$ Solve could find that special solution assuming that the argument in it is appropriately restricted, otherwise there is no simple way to list most likely infinitely many solutions of the equation at hand. Take a look at e.g. Can Reduce really not solve for x here? and How to solve a coupled system of transcendental equations? $\endgroup$ – Artes Sep 1 '20 at 22:37
  • $\begingroup$ Solve[1/3 Exp[-x/5] == Cos[x] && 0 < x < 200 Pi, x] worked like a charm...thank you $\endgroup$ – jamie Sep 1 '20 at 22:59

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