1.

Show that the modulusfunction `f: R->R`, given by `f(x)=|x|`is neither one-one noronto.

Answer» We have `f(-1) =|-1| =1 " and " f(1) =|1| =1`
Thus two different elements in R have the same image
`:.` f is not one-one
If we consider -1 in the codomain R then it is clear that there is no real number x whose modulus is -1
Thus -1 `in R ` has no pre- image in R
`:. ` f is not onto.
Hence f is neither one-one nor onto.


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