Advanced Math practice question

Answer: 8

x² − 9 = 0 gives x = 3 or x = −3, and x + 3 ≠ 0 rules out −3. So x = 3 and x + 5 = 8.

Common wrong answers

If you answered 2

2 uses x = −3, which is excluded.

If you answered 3

3 is x, but the question asks for x + 5.

If you answered 14

14 comes from x = 9, forgetting to take the square root.

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