Advanced MathMediumMaximum of a quadratic in standard form
Advanced Math practice question
The function q is defined by q(x) = −x² + 4x + 5. What is the maximum value of q(x)?
- A. 9Correct
- B. 5
- C. 2
- D. 4
Answer: A. 9
The vertex is at x = −b/(2a) = −4/(−2) = 2, and q(2) = −4 + 8 + 5 = 9.
Why the other answers are wrong
- B. 5
- 5 is q(0), the y-intercept.
- C. 2
- 2 is the x-coordinate of the vertex, not the maximum value.
- D. 4
- 4 is the coefficient b.
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