Advanced Math practice question

Answer: 7

x² + (3 − k)x + 4 = 0 has one solution when (3 − k)² = 16, so 3 − k = ±4 and k = −1 or k = 7. Since k > 0, k = 7.

Common wrong answers

If you answered 3

3 is the parabola's linear coefficient.

If you answered 4

4 is the square root of 16, not k.

If you answered -1

−1 is the negative value of k.

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