1.

The difference between two positive number is 5 and the sum of square of the numbers is 123. Find the square root of product of these number.1. 492. 643. 74. 63

Answer» Correct Answer - Option 3 : 7

Given :-

Difference between two positive number = 5

sum of their number of their square = 73

Concept :- 

(a - b)2 = a2 + b2 - 2ab

Calculation :-

Let first number be x 

⇒ Second number = y 

From question

⇒ x - y = 5    .....(1)

Again from question 

⇒ x2 + y2 = 123    ....(2) 

Now squaring both side of equation (1)

⇒ (x - y)2 = 52

⇒ x2 + y2 - 2xy = 25    ....(3)

Now put the value of equation (2) in equation (3)

⇒ 123 - 2xy = 25

⇒ 2xy = 123 – 25 

⇒ 2xy = 98 

⇒ xy = (98/2)

⇒ xy = 49

Now 

⇒ Square root of xy = √49 

⇒ Square root of xy = 7

∴ Square root of xy is 7


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