arrow
arrow
arrow
The difference between the squares of two numbers is 39 and the sum of these two numbers is 13. What are those numbers?
Question

The difference between the squares of two numbers is 39 and the sum of these two numbers is 13. What are those numbers?

A.

4, 3

B.

10, 3

C.

8, 5

D.

7, 6

Correct option is C

Given:

The difference between the squares of two numbers = 39

The sum of these two numbers = 13

Formula Used:

a2b2=(a+b)(ab)a^2 - b^2 = (a + b)(a - b)​​

Solution:

Let the two numbers be a and b.

Given a2b2^2 - b^2 ​= 39 and a + b = 13:

a2b2=(a+b)(ab)a^2 - b^2 = (a + b)(a - b)​​

39 = 13 × (a - b)

ab=3913=3a - b = \frac{39}{13} = 3​​

a - b = 3  , a + b = 13

Adding these two equations:

(a + b) + (a - b) = 13 + 3

2a = 16

a = 8

Substituting a = 8 into a + b = 13:

8 + b = 13

b = 5

The two numbers are 8 and 5.

Free Tests

Free
Must Attempt

CBT-1 Full Mock Test 1

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

RRB NTPC Graduate Level PYP (Held on 5 Jun 2025 S1)

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
Free
Must Attempt

RRB NTPC UG Level PYP (Held on 7 Aug 2025 S1)

languageIcon English
  • pdpQsnIcon100 Questions
  • pdpsheetsIcon100 Marks
  • timerIcon90 Mins
languageIcon English
test-prime-package

Access ‘RRB NTPC’ Mock Tests with

  • 60000+ Mocks and Previous Year Papers
  • Unlimited Re-Attempts
  • Personalised Report Card
  • 500% Refund on Final Selection
  • Largest Community
students-icon
368k+ students have already unlocked exclusive benefits with Test Prime!
Our Plans
Monthsup-arrow