Hi Ray,
Taking exp() of both sides makes finding the third root easy. I didn't think
of that.
Thanks,
Rich
-----Original Message-----
From: Raymond Toy
Sent: Friday, January 04, 2013 3:55 PM
To: maxima at math.utexas.edu
Subject: Re: [Maxima] Find roots
>>>>> "Richard" == Richard Hennessy <rich.hennessy at verizon.net> writes:
Richard> This challenge might be interesting to some people. Try to
find the
Richard> three real roots to log(x^3-x*78+90)+x. I had a hard time with
it.
Because of the three real zeroes of x^3-x*78+90, the log function
makes it difficult. I transformed the equation to
(x^3-x*78+90)*exp(x)=1 and found the roots of that. A plot of the
original function gives a rough idea of where the roots are: near -6,
1, and 8.
Ray
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