Write the set of values of k for which f(x) = kx – sinx is increasing on R.
f(x) = kx – Sin x
f’(x) = k – Cos x
For, f(x) to be increasing, it must have
f’(x) > 0
k – Cos x > 0
k > Cos x
Cos x < k
the minimum value of Xos x is 1.
Also, Cos x < k
The minimum value of k is 1.
k ϵ (1, ∞)
Hence the required set of values is k ϵ (1, ∞).