Question

Let the function $f: R \rightarrow R$ be defined by $f(x)=2 x+\cos x$. Then $f$ is

• A. has maximum at $x=0$
• B. has minimum at $x=\pi$
• C. is an increasing function
• D. is a decreasing function

Answer 1

Answer: (C)

$f(x)=2 x+\cos x$
$f'(x)=2-\sin x >0$
$f(x)$ is increasing function