Advanced Math practice question

Answer: A. −1

x(x + 2) = x² + 2x, and (x + 1)² = x² + 2x + 1. Subtracting: x² + 2x − x² − 2x − 1 = −1, whatever x is.

Why the other answers are wrong

B. 1

The sign is wrong: the square is larger by 1, so the difference is −1.

C. 2x − 1

2x − 1 forgets that the 2x terms cancel as well as the x² terms.

D. −2x − 1

−2x − 1 subtracts the square's 2x but forgets the product's own 2x, which cancels it.

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