Target Exam

CUET

Subject

-- Applied Mathematics - Section B2

Chapter

Calculus

Question:

If $1< x < 2, $ then which of the following is minimum ?

Options:

$-\frac{1}{x^3}$

$\frac{1}{x}$

$-\frac{1}{x^4}$

$-\frac{1}{x^2}$

Correct Answer:

$-\frac{1}{x^2}$

Explanation:

The correct answer is Option (4) → $-\frac{1}{x^2}$

$x^4>x^3>x^2$

$∴\frac{1}{x^4}<\frac{1}{x^3}<\frac{1}{x^2}$ (Since x is positive $1<x<2$)

$⇒\frac{-1}{x^4}>\frac{-1}{x^3}>\frac{-1}{x^2}$

$∴\frac{-1}{x^2}$ is minimum