Advanced Math practice question

Answer: 10

(a + b)² − (a − b)² = 4ab, so 4ab = 40 and ab = 10.

Common wrong answers

If you answered 20

20 halves 40 instead of quartering it.

If you answered 29

29 is a² + b², half the sum of the two squares.

If you answered 40

40 is 4ab.

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