[Free42] root finder

[Gerson W. Barbosa]

(06-15-2016 12:23 AM)Marcio Wrote:  On page 184 of the 15C's user guide, one can find the following equation:
\[h = 5000\left(1-e^{-t/20}\right)-200t \]
which is solved for t when h=0.

That's a job for WP 34S and its buit-in Lambert W function:

5 ENTER 4 +/- / f e^x RCL* L Wp 20 * 25 + --> 9.284255087576332994076124612599270

Not the answer to your question, sorry, but at least 34 digits for you to check upon the Free42 result :-)