Advanced Math practice question

Answer: 5

Let u = x + 3: u² − u − 6 = (u − 3)(u + 2) = (x + 3 − 3)(x + 3 + 2) = x(x + 5). So a = 0, b = 5, and a + b = 5.

Common wrong answers

If you answered 3

3 comes from a = 3 and b = 0, misplacing the substitution.

If you answered 11

11 comes from (x + 6)(x + 5), adding 3 to both factors instead of substituting.

If you answered -1

−1 is the sum of the constants in (u − 3)(u + 2), before substituting back for u.

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