Which describes $f(x) = 5 - 3x$ ?

Strictly increasing on

\mathbb{R}

Correct answerYour answerIncreasing on one part of

\mathbb{R}

and decreasing on anotherCorrect answerYour answerConstant on

\mathbb{R}

Correct answerYour answerStrictly decreasing on

\mathbb{R}

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer D

Correct answer: D

For $x_1 < x_2$ , $-3x_1 > -3x_2$ , so $5 - 3x_1 > 5 - 3x_2$ : a larger $x$ always gives a smaller value.
So $f$ is strictly decreasing on $\mathbb{R}$ ; its derivative, $-3$ , says the same.

Worth noting

The constant term 5 is positive, but it only moves the line up; the slope $-3$ decides.

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

Which describes f(x)=5−3xf(x) = 5 - 3xf(x)=5−3x?