# ISI B.Math Entrance(6)

Algebra Level 4

Let $$\text{sgn} (x)$$ denote the signum function.

Find the number of discontinuities in the function $$f(x)=(x+1)\text{sgn }(x^2-1)$$, where $$f: \mathbb R \to \mathbb R$$ where $$\mathbb R$$ is the set of all real numbers.

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