labyrinth9 wrote:f(4) = derivative(integral(f(x)))|x=4, since they are inverses.
So, we can represent n/(4^(n+1)) as
Therefore, we have the ans is equal to
d/dx[SUM[-(1/x)/(1-(1/x))]]|x=4, since d/dx is linear
ps. Sorry I don't know LaTeX... I really should learn.
Thanks for the nice explanation, I should be able to handle this type of questions now.
is quite interesting and the basics are to learn! You should read the lshort file if you have time, it is quite helpful.