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# Improper Integrals watch

1. I'm trying to evaluate the integral:

So I get that the integration itself is reverse chain rule and very simple, however I'm not sure how to express the result of the integral as tends to infinity. Please could someone give me some pointers? Thanks.
2. (Original post by Texx)
I'm trying to evaluate the integral:

So I get that the integration itself is reverse chain rule and very simple, however I'm not sure how to express the result of the integral as tends to infinity. Please could someone give me some pointers? Thanks.
replace the infinity with a leter say k
carry the integration with limits
get answer in terms of k
let k tend to infinity

look at 3 examples to see my notation for this type of work

improper_integrals.pdf
3. (Original post by TeeEm)
replace the infinity with a leter say k
carry the integration with limits
get answer in terms of k
let k tend to infinity

look at 3 examples to see my notation for this type of work

improper_integrals.pdf
Okay so I replaced infinity with k and integrated to get:

What would I write for my final answer for this? Would I just say that it tends to infinity?
4. (Original post by Texx)
Okay so I replaced infinity with k and integrated to get:

What would I write for my final answer for this? Would I just say that it tends to infinity?
write it as 1/(x+3)2
then as k tens to infinity 1/(x+3)2 tends to zero
so 1/18
5. (Original post by TeeEm)
write it as 1/(x+3)2
then as k tens to infinity 1/(x+3)2 tends to zero
so 1/18
Sorry, I was half asleep when I wrote that. Yeah, that makes sense, thanks for helping.
6. (Original post by Texx)
Sorry, I was half asleep when I wrote that. Yeah, that makes sense, thanks for helping.
no worries

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