It is given that f : R → R, given by
We can observed that f(1) = f(2) = but 1 ≠ 2.
Thus, f is not one – one.
Now, as f(x) takes only 3 values (1, 0, -1) for the element -2 in co-domain R, there exists any x in domain R such that f(x) = -2
Thus, f is not onto.
Therefore, the signum function is neither one-one nor onto.
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