I was doing this problem about optimization and I derived it to:(adsbygoogle = window.adsbygoogle || []).push({});

R' = (1-lnx)/x^{2}

(This was the right derivative by the way as the maximum on the R function was the same answer as when R' = 0)

Anyways as R' = 0 when stationary points occur:

0 = (1-lnx)/x^{2}

I was wondering whether it was possible to do that without the help of a graph/graphics calculator because of the zero there. I managed to get the correct answer which was x=2.71 but I couldn't do it manually because of the zero even when I used the null factor law (1-lnx) = 0 or 1/x^{2}= 0.

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Is this possible without a calculator?

**Physics Forums | Science Articles, Homework Help, Discussion**