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  1. The sum of the square of two numbers is 97 and the square of their difference is 25. The product of the two number is
    1. 45
    2. 36
    3. 54
    4. 63
Correct Option: B

Let the two number are a and b
According to the question
sum of squares of two numbers = 97
i.e.., a 2 + b 2 = 97 .....................(i)
and square of their difference = 25
i.e., (a - b) 2 = 25 .................(ii)
⇒ a - b = 5...............(iii)
from Eq. (ii)
a2 + b2 - 2ab = 25
(a2 + b2) - 2ab = 25
Now put the value of a 2 + b 2 from Eq. (i)
⇒ 97 - 2ab = 25
⇒ 2ab = 72
⇒ ab = 36.................(iv)
Now, we have
(a + b)2 = ( a2 + b2) + 2ab
Now put the value of a 2 + b 2 from Eq. (i) and ab from Eq. (iv)
(a + b)2 = 97 + 72 = 169
a + b = 13.............(v)
Now add the Eqs. (iii) and (v), we get
a - b + a + b = 5 +13
2a = 18
⇒ a = 9
now put the value of a in Eq. (v)
a + b = 13
9 + b = 13
b = 13 - 9
b = 4
∴ Product of both the numbers = ab = 9 x 4 = 36



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