Advanced Math practice question

Answer: 3

Set the two expressions for y equal: x² − 4 = 3x, so x² − 3x − 4 = 0. Factor: (x − 4)(x + 1) = 0, giving x = 4 or x = −1. Both check (16 − 4 = 12 = 3·4, and 1 − 4 = −3 = 3·(−1)). The sum is 4 + (−1) = 3.

Common wrong answers

If you answered 4

4 is only one of the two x-values. The system has two solutions, and the question asks for the sum of both x-coordinates.

If you answered 5

4 + 1 = 5 uses the wrong sign on the second root. (x + 1) = 0 gives x = −1, so the sum is 4 − 1 = 3.

If you answered 9

9 is the sum of the y-values (12 + (−3)). The question asks about the x-coordinates.

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