How To apply Binomial Therem For, Z = 0 and Z >> R

[urduworld]

http://www.physicsforums.com/attachment.php?attachmentid=18937&stc=1&d=1242541916

Hi Friends Please Solve my problem

Please TEll Properly

dq = Surface Charge
da = Surface Area
Radius of ring = w
Total Radius = R
qo = Point Charge
Distance from Center of Ring to Point Charge = Z

I want to know how I ca apply binomial theorem to solve the equation
If
Z = 0
Z >> 0 (Very greater)

[urduworld]

plz answer me

[AUMathTutor]

This is a physics question. You will have more luck there, or in the physics sections of the Homework subforum.