Question

\[ \int_0^{2\pi} \int_0^{12} e^{-r} r \,\textrm{d}r\,\textrm{d}\theta \]

Answer 1

use integration by parts on the inside integral

Answer 2

i don't think so !

Answer 3

I do

Answer 4

haha ! ok ! i'll try !

Answer 5

u=r
du=dr
\[dv=e^{-r}dr\]
\[v=-e^{-r}\]

Answer 6

evaluate that at 12 !?

Answer 7

0.000878622367 ?

Answer 8

no...evaluate at 0 and 12

Answer 9

\[\int\limits_{0}^{12}e^{-r}r\,dr=1-13e^{-12}\approx.999920125239\]

Answer 10

oh ok ! cool thanks