Advanced Math practice question

Answer: −16 or -16

The zeros are x = 2 and x = −6. The vertex lies midway between them, at x = (2 + (−6))/2 = −2. Substitute: f(−2) = (−4)(4) = −16. The parabola opens upward, so that is the minimum.

Common wrong answers

If you answered 16

The sign is wrong: (−4)(4) = −16. The parabola dips below the x-axis between its zeros.

If you answered −2

−2 is the x-coordinate WHERE the minimum occurs. The minimum VALUE is f(−2) = −16.

If you answered −12

−12 is the y-intercept, f(0) = (−2)(6). The minimum is at x = −2, not x = 0.

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