Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Calculus

Question:

The minimum value of the function $f(x)=x^2+\frac{128}{x}$ is :

Options:

64

48

112

96

Correct Answer:

48

Explanation:

The correct answer is Option (2) → 48

$f(x)=x^2+\frac{128}{x}$

$f'(x)=2x-\frac{128}{x^2}$

for critical points,

$f'(c)=0$

$⇒2c-\frac{128}{c^2}=0$

$⇒2c^3=128$

$⇒c^3=64$

$⇒c=4$

$f(4)=16+\frac{128}{4}=48$