If $f : R \rightarrow R$ be defined by $f(x) = 2x + \cos x$, then $f$
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → is an increasing function ##
We have,
$f(x) = 2x + \cos x$
$∴f'(x) = 2 + (-\sin x) = 2 - \sin x$
Since, $f'(x) > 0, \forall \ x$
Hence, $f(x)$ is an increasing function.