Answer
$=\frac{1}{3}$
Work Step by Step
Factor each polynomial:
$$\lim_{x\to 1}\frac{x-1}{x^3-1}\\=\lim_{x\to 1}\frac{(x-1)}{(x-1)(x^2+x+1)}.$$
Cancel the common factors: $$\lim_{x\to 1}\frac{1}{(x^2+x+1)}\\=\frac{1}{(1^2+1+1)}\\=\frac{1}{3}$$