[math-fun] a^x-b^x=c, solve for x ?
I can solve this equation with Newton's iterations, but I was curious if there might be an elegant closed form solution. I tried fiddling with hyperbolic trig functions, but nothing seemed any simpler. real a>b>0,c>0 E.g., a ~ 50, b ~ 49, c ~ 2 => x ~ 1.1438929
For what it's worth maple solves 50^x - 49^x = 2 more or less instantly giving: x=1.14331628080253252585595933. I have no idea what it is doing inside the "fsolve" routine. On Fri, Oct 19, 2018 at 2:44 PM Henry Baker <hbaker1@pipeline.com> wrote:
I can solve this equation with Newton's iterations, but I was curious if there might be an elegant closed form solution.
I tried fiddling with hyperbolic trig functions, but nothing seemed any simpler.
real a>b>0,c>0
E.g., a ~ 50, b ~ 49, c ~ 2 => x ~ 1.1438929
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