Radius of convergence of $x$

Question

What is the radius of convergence of $f(x)=x$?

I have found the taylor series of x to be just = $1 + (x-1)$ , but then how can I use the ratio test to determine the radius? Or is there another way?

Answer 1

If the Taylor series terminates, so that the function is just a polynomial, there's no need to use an indirect test to find the radius of convergence. Clearly the series converges for all real numbers, because it is just a finite sum.