Approximating E using Taylor's Formula when d/z is small

[BraedenP]

What is a "Small" Number?

Homework Statement

I am given the equation, and asked to find an approximation (using Taylor's Formula):
$$E=\frac{q}{z^2(1-d/z)^2}-\frac{q}{z^2(1+d/z)^2}$$
I am also told that I can assume "z is much larger than d, so d/z is small."

Does this mean that I can assume d/z = 0? This seems to be what that quote is suggesting.

Is this what it's referring to?

Homework Equations

The Attempt at a Solution

Nada.

 

[Dick]

No, you can't put d/z=0. Saying d/z is 'small' means |d/z|<<1. So small that you can put (d/z)^2 approximately equal to zero. I.e. ignore it compared with d/z.