Advanced Math practice question

Answer: A. 12x + 18

2(x + 3)² = 2(x² + 6x + 9) = 2x² + 12x + 18. Subtracting 2x² leaves 12x + 18.

Why the other answers are wrong

B. 18

18 drops the 12x term produced by the square's middle term.

C. 6x + 18

6x + 18 forgets to multiply the middle term 6x by the 2 outside.

D. 12x + 9

12x + 9 forgets to multiply the 9 by 2.

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