Advanced Math practice question

Answer: 2

(a + b)² + (a − b)² = (a² + 2ab + b²) + (a² − 2ab + b²) = 2a² + 2b² = 2(a² + b²). So k = 2.

Common wrong answers

If you answered 0

0 confuses this with the difference of the two squares, which is 4ab.

If you answered 1

1 forgets that each square contributes a² and b².

If you answered 4

4 counts the cross terms as adding instead of cancelling.

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