1. completely monotone condition

Hi all,
Can someones suggest or give me some hint to do that.
Find the condition of a > 0, b > 0 and c>0 so that function: f(x)=e-ax/(1+c e-bx) is completely monotone.
I found the condition at 1st and 2nd derivative but can't do for all derivative order.
Thanks,

2. Re: completely monotone condition

Hey widapol.

Can you show us what you got for the first and second derivatives? If you show that the derivative is always increasing (or decreasing) across the entire interval, then that's all you have to do.