Give examples of two surjective function `f_1` and `f_2` from `Z` to `Z` such that `f_1+f_2` is not surjective.

Explanation

Let a function `f:A->B`is said to be a onto function or surjective if every elemnt of A i.e, if `f(A)=B` or range of f is the co-domain of f.

So, `f:A->B` is surjective for each `b∈B`, there exists `a∈B `such that `f(a)=b`

Let` f_1:Z->Z` and `f_2:Z->Z `be two functions given by

`impliesf_1(x)=x`

`impliesf_2(x)=-x`

From above function it is clear that both are surjective functions.

Now,

`impliesf_1+f_2:Z->Z`

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