1.

If a - b = 5 and a2 + b2 = 31 then find the value of ab?A. 4B. 5C. 2D. 31. C2. A3. B4. D

Answer» Correct Answer - Option 4 : D

Given:

a - b  = 5

a2 + b2 = 31

Formula used:

(a - b)2 = a2 + b2 - 2ab

Calculation:

(a - b)2 = a2 + b2 - 2ab

⇒ 52 = 31 - 2ab

⇒ 25 = 31 - 2ab

⇒ 2ab = 31 - 25

⇒ 2ab = 6

⇒ ab = 3

∴ The value of ab is 3.



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