How do I expand a bracket to a negative power if it doesn't start with a 1.

Okay so consider (2 + x)^-1, we can only do the expansion we know if the bracket starts with a 1, to fix this we can factor a 2 out of the bracket so that it becomes (2(1 + x/2))^-1. Then by our rules of powers this is the same as 2^(-1)(1 + x/2)^(-1), 2^-1 = 1/2 and we can expand the remaining bracket as we have done before, so to get the first 3 terms we'd have:1/2(1 + (-1)(x/2) + (-1)(-2)(x/2)^2/2!)= 1/2(1 - x/2 + x^2/4)= 1/2 - x/4 + x^2/8