I agree the proper category is calculus.

However, there is a solution  requiering neither the use of the series nor the explicit calculation of values- just checking the sign of the derivative of a certain function.

Calculus- yes;  calculation  -   no. 

Did I disclose too  much?

 ==

 Rem: a "double negative" grammar error corrected.

Edited on April 30, 2016, 3:35 am

Posted by Ady TZIDON on 2011-07-27 23:57:17