Find `' a '` for which `f(x)=a\ (x+sinx)+a` is increasing on `R` .

Explanation

We have given

`f(x)=a(x+sinx)+a`

Then,

`f'(x)=a(1+cosx)`

Then

`−1``\leq``cosx``\leq``1`

Then,

`1+cosx``\geq``0`

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