If $x+2y=8$ then the maximum value of

CUET Preparation Today

Start Free Mocks

Home Questions W7E4N6Q4JV

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Applications of Derivatives

Question:

If $x+2y=8$ then the maximum value of $xy$ is

Options:

$20$

$16$

$24$

$8$

Correct Answer:

$8$

Explanation:

Let $f(y)=(8-2y)y=8y-2y^{2}$ $f^{\prime}(y)=8-4y,f^{\prime}(y)=0\Rightarrow y=2\hspace{7cm}$ Max $(f(y))=16-8=8$