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If a2+b2=50 a^2+b^2=50a2+b2=50​ and a×b =7. Find (a−b)(a+b)\frac{(a-b)}{(a+b)}(a+b)(a−b)​​, where a>b.
Question

If a2+b2=50 a^2+b^2=50​ and a×b =7. Find (ab)(a+b)\frac{(a-b)}{(a+b)}​, where a>b.

A.

3/5

B.

4/3

C.

5/3

D.

3/4

Correct option is D

Given:

a2+b2=50a^2+b^2=50

ab = 7

Concep used:

Using the identity for (a+b)2(a + b)^2​ and (ab)2(a - b)^2

(a+b)2=a2+b2+2ab(a+b)^2=a^2+b^2+2ab

​​(ab)2=a2+b22ab(a−b)^2=a^2+b^2−2ab​​

Solution:

we calculate a + b and a - b:

(a+b)2(a+b)^2 = 50 +2 ×\times​7 = 50+14 = 64

(ab)2(a−b)^2 = 50- 2×\times​7 = 50-14 = 36

So,

a+b = 64\sqrt64 = 8 (take positive root as a +b > 0)

​a−b = 36\sqrt36 = 6 (take positive root as a>b)

​Now, we can find aba+b:\frac{a−b}{a+b}:

​​aba+b\frac{a−b}{a+b} = 34\frac{3}4

Thus, correct option is (d)

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