Find the set of values of `' a '` for which `f(x)=x+cosx+a x+b` is increasing on `R` .

Explanation

`f(x)=x-cos x-a x+b `

`f^{prime}(x)=1-sin x+a+0 `
`
f^{prime}(x)=1-sin x+a`


For, f(x) to be increasing, it must have


`f^{prime}(x)=0`
`
therefore 1-sin x+a>0 `
`
...