(2) f(x) = 1/(x+1) = 1/[2 + (x-1)] = (1/2) /[1+(x-1)/2]= (1/2)∑ (-1)^n [(x-1)/2]^n = ∑ (1-x)^n / 2^(n+1) -1 < (x-1)/2 < 1, -1 < x < 3
