Mathematical Physics: Bessel functions of the first kind property

[M. next]

I ran into some formula:

$^{a}_{0}$∫J$_{o}$(kr) rdr= a/k J$_{1}$(ka)

How can this be true? What property was used?

 

[jasonRF]

Try writing down the series representation of $J_0(kr)$ and integrate term by term.