consider the geometric series, with |x|<1: S=1+x+x^2+x^3+...=1/(1-x) as x goes to -1 from right, S goes to 1/2.

## what about using limit for 1-1+...

consider the geometric series, with |x|<1:

S=1+x+x^2+x^3+...=1/(1-x)

as x goes to -1 from right, S goes to 1/2.