\(\lim\limits _{x \to 0^-}\) f(x) = \(\lim\limits _{x \to 0}\) -1 = -1
\(\lim\limits _{x \to 0^+}\) f(x) = \(\lim\limits _{x \to 0}\) 1 = 1
Therefore; \(\lim\limits _{x \to 0^-}\) f(x) \(\neq\)\(\lim\limits _{x \to 0^+}\)f(x)
Hence \(\lim\limits _{x \to 0}\) f(x) does not exist