Hey I am having trouble with improper integrals. I have like 5-6 problems that I am just super stuck on. I have read the chapter like 2-3 times and still don't understand it.

The problems:

1) int -2 to infinity 2 dx / (x^2-1)

this I think can be broken up into two integrals

2/(x+1) + 2/(x-1) and then these are both du/u problems.

so we have

lim b-> infinity int -2 to b 2/(x+1) + 2/(x-1)

now I am stuck.

2)

int -infinity to -2 2 dx/(x^2-1)

can anyone give me a shove in the right direction please?

3)

int -infinity to infinity 2x dx/(x^2+1)^2

another du/u Im assuming

but how do you deal with a -infinity to infinity improper integral

another shove please?

I would greatly appreciate any help to get these started