Is ithe function F(x) = 1/2x + 1 or 1/(2x+1)?
Either way the linearization is L(x) = f(-1) + f'(-1)(x+1)
You need to find the derivative. Evaluate f(x) and f'(x) at x = -1. Sub into the formula the value of (x+1) that you want to put in the table in order to get L(x). Obviously, f(x) is just plugging x into the function to see how good the linearization is.