Advanced Math practice question

Answer: 5

Let u = x²: u² − 13u + 36 = 0 → (u − 4)(u − 9) = 0 → x² = 4 or x² = 9. The positive solutions are 2 and 3, whose sum is 5.

Common wrong answers

If you answered 0

0 is the sum of all four solutions (±2, ±3).

If you answered 6

6 is 2 × 3, the product.

If you answered 13

13 is the sum of x² values (4 + 9), not of x values.

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