If a - b = 3 and a2 + b2 = 29, find the value of ab.

Q: If a - b = 3 and a2 + b2 = 29, find the value of ab.

2 ab = ( a 2 + b 2 ) - ( a - b ) 2 = 29 - 9 = 20 ⟹ab = 10.

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Correct Answer: 10

Explanation:

2 ab = ( a ² + b ² ) - ( a - b ) ²

= 29 - 9 = 20

⟹ab = 10.

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