Which of the following statement is correct?

I. The value of 1002 - 992 + 98972 + 962 - 952 + 942 - 932 + ......  + 22 - 212 is 4840.

II. The value of 

\(\left(k^2+ \frac{1}{k^2} \right) \left(k- \frac{1}{k} \right) \left(k^4+ \frac{1}{k^4} \right) \)\(\left(k+ \frac{1}{k} \right)\left(k^4- \frac{1}{k^4} \right)\) is \(k^{16}- \frac{1}{k^{16}}\).

This question was previously asked in
SSC CGL 2022 Tier-I Official Paper (Held On : 13 Dec 2022 Shift 3)
View all SSC CGL Papers >
  1. Neither I nor II
  2. Both I and II
  3. Only II
  4. Only I

Answer (Detailed Solution Below)

Option 4 : Only I
vigyan-express
Free
PYST 1: SSC CGL - General Awareness (Held On : 20 April 2022 Shift 2)
3.6 Lakh Users
25 Questions 50 Marks 10 Mins

Detailed Solution

Download Solution PDF

Concept used:

a2 - b2 = (a + b) × (a - b)

Ta + (n - 1) × d

Where, Tn = last term

a = first term, d = common difference and n = number of terms

Calculation:

if we take the first statement:

1002 - 992 + 98972 + 962 - 952 + 942 - 932 + ......  + 22 - 212 is 4840.

⇒ (100 + 99) × (100 - 99) + (98 + 97) × (98 - 97) ........ + (22 + 21) × (22 - 21)

⇒ 100 + 99 + 98 + 97 ........... + 22 + 21

Now, the series is in A.P

⇒ a + (n - 1) × d = Tn 

⇒ 100 + (n - 1) × (- 1) = 21

⇒ 100 - n + 1 = 21

⇒ - n = (21 - 101) = - 80

⇒ n = 80

Sum of the series : 100 + 99 + 98 + 97 ........... + 22 + 21

⇒ {(100 + 21)/2} × 80

⇒ 60.5 × 80 = 4,840

∴ The first statement is correct.

if we take the second statement:​​

\(\left(k^2+ \frac{1}{k^2} \right) \left(k- \frac{1}{k} \right) \left(k^4+ \frac{1}{k^4} \right) \) \(\left(k+ \frac{1}{k} \right)\left(k^4- \frac{1}{k^4} \right)\) is \(k^{16}- \frac{1}{k^{16}}\)

⇒ \(\left(k^2+ \frac{1}{k^2} \right) \left(k^2- \frac{1}{k^2} \right) \left(k^4+ \frac{1}{k^4} \right) \)\(\left(k^4- \frac{1}{k^4} \right)\)

⇒ \(\left(k^4- \frac{1}{k^4} \right) \left(k^4+ \frac{1}{k^4} \right) \)\(\left(k^4- \frac{1}{k^4} \right)\)

⇒ \(\left(k^8- \frac{1}{k^8} \right) \left(k^4- \frac{1}{k^4} \right) \) ≠ \(k^{16}- \frac{1}{k^{16}}\)

∴ The second statement is wrong.

∴ The correct option is 4.

Latest SSC CGL Updates

Last updated on Jun 13, 2025

-> The SSC CGL Notification 2025 has been released on 9th June 2025 on the official website at ssc.gov.in.

-> The SSC CGL exam registration process is now open and will continue till 4th July 2025, so candidates must fill out the SSC CGL Application Form 2025 before the deadline.

-> This year, the Staff Selection Commission (SSC) has announced approximately 14,582 vacancies for various Group B and C posts across government departments.

->  The SSC CGL Tier 1 exam is scheduled to take place from 13th to 30th August 2025.

->  Aspirants should visit ssc.gov.in 2025 regularly for updates and ensure timely submission of the CGL exam form.

-> Candidates can refer to the CGL syllabus for a better understanding of the exam structure and pattern.

-> The CGL Eligibility is a bachelor’s degree in any discipline.

-> Candidates selected through the SSC CGL exam will receive an attractive salary. Learn more about the SSC CGL Salary Structure.

-> Attempt SSC CGL Free English Mock Test and SSC CGL Current Affairs Mock Test.

-> Candidates should also use the SSC CGL previous year papers for a good revision. 

More Algebra Questions

Get Free Access Now
Hot Links: teen patti real cash apk teen patti gold new version teen patti baaz teen patti gold real cash teen patti gold new version 2024