Advanced Math practice question

Answer: 9

(2x + 1)² = 4x² + 4x + 1, so a + b + c = 4 + 4 + 1 = 9. (Shortcut: substitute x = 1: (3)² = 9.)

Common wrong answers

If you answered 3

3 is 2 + 1, the sum of the binomial's coefficients, not of the square's.

If you answered 5

5 comes from 4x² + 1, forgetting the middle term 4x.

If you answered 7

7 comes from a middle term of 2x (not doubling the cross product).

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