How to Reduce a Function to a Hypergeometric Using a Change of Variables?

[blocnt]

I'm having difficulty in solving an exercise.

http://imageshack.us/a/img542/484/765z.jpg

They ask to reduce it to
http://imageshack.us/a/img203/3986/lwqb.jpg
making the change of variables x=r^2/(r^2+1)

and then to reduce it to a hypergeometric , using http://img41.imageshack.us/img41/4479/syz6.jpg


Thanks in advance

 

[MathematicalPhysicist]

HW question, inappropriate.