convergence or divergence

[engineer12]

can anyone help with the convergence or divergence of the improper integral x2^-x dx from 0 to 8

I tried using the geometric series and couldn't get a defined answer

 

[Deleted member 4993]

can anyone help with the convergence or divergence of the improper integral x2^-x dx from 0 to 8

I tried using the geometric series and couldn't get a defined answer

Is your problem:

\(\displaystyle \displaystyle \int_0^8 x*2^{-x}dx\)

or something else?

Show us how far you went with geometric series.

Please share your work with us.

You need to read the rules of this forum. Please read the post titled "Read before Posting" at the following URL:

http://www.freemathhelp.com/forum/th...217#post322217

We can help - we only help after you have shown your work - or ask a specific question (e.g. "are these correct?")

 

[lookagain]

can anyone help with the convergence or divergence of the improper integral x2^-x dx from 0 to 8

I tried using the geometric series and couldn't get a defined answer

engineer12,

as Subhotosh Kahn already asked about, if the integrand is \(\displaystyle \ x(2^{-x}), \ \) then I would ask you if the limits of integration
are supposed to be 0 and \(\displaystyle \ oo, \ \ \) because nowhere is the function undefined on [0, oo].


Instead, it would make sense for the problem to ask about determining the convergence or divergence of



\(\displaystyle \displaystyle \int_0^{oo} x(2^{-x})dx\)