Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Applications of Derivatives

Question:

The interval in which $f(x)=x^2 e^{-x}+7$ is increasing is:

Options:

$(-\infty, \infty)$

$(-2,0)$

$(2, \infty)$

$(0,2)$

Correct Answer:

$(0,2)$

Explanation:

The correct answer is Option (4) → $(0,2)$

$y=x^2 e^{-x}+7$

$y'=2xe^{-x}-x^2e^{-x}=0$

$e^{-x}x(2-x)=0$

$⇒x=0,2$

f(x) increasing in (0, 2)