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The sum of two numbers is 20 and the difference between their squares is 80. Select the two numbers from the given options.
Question

The sum of two numbers is 20 and the difference between their squares is 80. Select the two numbers from the given options.

A.

13, 7

B.

15, 5

C.

11, 9

D.

12, 8

Correct option is D

Given:

Sum of two numbers = 20

Difference between their squares = 80

Concept Used:

Algebraic identities: a² - b² = (a + b)(a - b)

Solution:

Let the two numbers be 'a' and 'b'.

a + b = 20 .... (1)

a² - b² = 80

80 = (20)(a - b)

a - b = 4 .....(2)

Adding the two equations:

2a = 24

a = 12

Substituting the value of 'a' in the first equation:

12 + b = 20

b = 20 - 12

b = 8

The two numbers are 12 and 8.

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