Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

The greatest integer function $f(x) = [x]$ is differentiable for all values of

Options:

$x ∈Z$ (set of integers)

$x∈R$ (set of real number)

$x ∈R-Z$

$x ∈ Q$ (set of rational number)

Correct Answer:

$x ∈R-Z$

Explanation:

The correct answer is Option (3) → $x ∈R-Z$

The greatest integer function $f(x)=[x]$ has jump discontinuities at every integer.

Hence it is:

• Not continuous at integers • Therefore not differentiable at integers

But it is continuous and differentiable for all non-integer real numbers.

So $f(x)$ is differentiable for all $x\in \mathbb{R}-\mathbb{Z}$.