Advanced Math practice question

Answer: 4

Factor x² − 2x − 8: we need two numbers that multiply to −8 and add to −2 — those are +2 and −4, so (x + 2)(x − 4). Matching to (x + 2)(x − a) gives a = 4.

Common wrong answers

If you answered 2

That's the number in the *other* factor, (x + 2). Match the second factor: (x − 4) means a = 4.

If you answered -4

You found the right factorization, (x + 2)(x − 4), but the form is (x − a), so a = 4, not −4 — the minus sign is already built into the expression.

If you answered -2

You read a off the (x + 2) factor. The problem pairs (x + 2) with (x − a), so a comes from the second factor, x − 4, giving a = 4.

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