Take the 2-minute tour ×
MathOverflow is a question and answer site for professional mathematicians. It's 100% free, no registration required.

Given: \begin{equation} f_1(a)=\sum_{i=1}^{k^*-1} \left(\begin{array}{c} K \\\ i \\ \end{array} \right) \left(-1-\frac{1}{ar}\right)^i \end{equation} \begin{equation} f_2(a)=\sum_{i=1}^{k^*-1} \left(\begin{array}{c} K\\\ i \end{array} \right) \left(-1+\frac{1}{a}\right)^i \end{equation} prove or disprove that \begin{equation} f_3(a)=\frac{f_1(a)}{f_2(a)} \end{equation} is an increasing funtion of $a$, where $-1< r < 0$ and $0.5 < a < 1$

share|improve this question
Why should we? Where does this question come from? And what is $k^*?$ –  Igor Rivin Apr 24 '12 at 23:23
This question is a part of a more general proof in detection theory where I am working on. $k^{*} > 2$ and $K > k^{*}$ both $k^{*}$ and $K$ are integers. –  Seyhmus Güngören Apr 24 '12 at 23:39
obviously for $k^{*} \geq 2$ too. I will be happy if I will get any answer.d Thanks alot for the visitors of my question.. –  Seyhmus Güngören Apr 24 '12 at 23:47
For the record, I don't think your tags are very appropriate. –  Thierry Zell Apr 25 '12 at 1:25

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.