Comprehension

Consider the following for the two (02) items that follow:
Let f(x) = [x2] where [.] is the greatest integer function.

\(\int_{\sqrt{2}}^{2} f(x) dx\)  is equal to ?

This question was previously asked in
NDA-I (Mathematics) Official Paper (Held On: 13 Apr, 2025)
View all NDA Papers >
  1. \(6-\sqrt{3}-2\sqrt{2}\)
  2. \(6-\sqrt{3}-\sqrt{2}\)
  3. \(6-\sqrt{3}+2\sqrt{2}\)
  4. \(6+\sqrt{3}-2\sqrt{2}\)

Answer (Detailed Solution Below)

Option 1 : \(6-\sqrt{3}-2\sqrt{2}\)
Free
UPSC NDA 01/2025 General Ability Full (GAT) Full Mock Test
6 K Users
150 Questions 600 Marks 150 Mins

Detailed Solution

Download Solution PDF

Calculation:

Given,

The function is \( f(x) = \lfloor x^2 \rfloor \).

We are tasked with finding the value of \( \int_{\sqrt{2}}^{2} f(x) dx \).

We can break the integral into two parts as follows:

\( \int_{\sqrt{2}}^{2} f(x) dx = \int_{\sqrt{2}}^{\sqrt{3}} 2 dx + \int_{\sqrt{3}}^{2} 3 dx \)

For the range \( \sqrt{2} \leq x \leq \sqrt{3} \), \( \lfloor x^2 \rfloor = 2 \). So the first part of the integral is:

\( \int_{\sqrt{2}}^{\sqrt{3}} 2 dx = 2 \times (\sqrt{3} - \sqrt{2}) \)

For the range \( \sqrt{3} \leq x \leq 2 \), \( \lfloor x^2 \rfloor = 3 \). So the second part of the integral is:

\( \int_{\sqrt{3}}^{2} 3 dx = 3 \times (2 - \sqrt{3}) \)

Now, we calculate the values:

\( 2 \times (\sqrt{3} - \sqrt{2}) = 2\sqrt{3} - 2\sqrt{2} \)

\( 3 \times (2 - \sqrt{3}) = 6 - 3\sqrt{3} \)

Combining the two parts:

\( 2\sqrt{3} - 2\sqrt{2} + 6 - 3\sqrt{3} = 6 - 2\sqrt{2} - \sqrt{3} \)

Hence, the correct answer is Option 1.

Latest NDA Updates

Last updated on Jul 8, 2025

->UPSC NDA Application Correction Window is open from 7th July to 9th July 2025.

->UPSC had extended the UPSC NDA 2 Registration Date till 20th June 2025.

-> A total of 406 vacancies have been announced for NDA 2 Exam 2025.

->The NDA exam date 2025 has been announced. The written examination will be held on 14th September 2025.

-> The selection process for the NDA exam includes a Written Exam and SSB Interview.

-> Candidates who get successful selection under UPSC NDA will get a salary range between Rs. 15,600 to Rs. 39,100. 

-> Candidates must go through the NDA previous year question paper. Attempting the NDA mock test is also essential. 

Get Free Access Now
Hot Links: teen patti 3a teen patti master update teen patti chart