Write the set of values of `k` for which `f(x)=k x-sinx` is increasing on `R` .

Explanation

`f(x)=k x-sin x`
`


f^{prime}(x)=k-cos x`


for increasing `f^{prime}(x) ge 0`
`

k-cos x geq 0 forall x in R`
`
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