Which describes $f(x) = 2 x + \cos x$ ?

Strictly decreasing on

\mathbb{R}

Correct answerYour answerStrictly increasing on

\mathbb{R}

Correct answerYour answerIncreasing on one part of

\mathbb{R}

and decreasing on anotherCorrect answerYour answerConstant on

\mathbb{R}

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer B

Correct answer: B

$f'(x) = 2 - \sin x$ .
Here $2 - \sin x \ge 1 > 0$ , since $\sin x \le 1$ , so $f$ is strictly increasing on $\mathbb{R}$ .

Ten questions from Increasing & Decreasing Functions, at your own pace.

Ten questions from Increasing & Decreasing Functions, at your own pace.

Which describes f(x)=2x+cos⁡xf(x) = 2 x + \cos xf(x)=2x+cosx?