Set 13: Quadratic Equations

Explanation

Answer: A

Which feature is NOT visible directly from the standard form $y = ax^2 + bx + c$ ?

The vertex coordinates

✓ Correct

The y-intercept

The direction of opening

The vertical stretch factor

Detailed Explanation

Choice A is correct. Choice A is the correct answer. * A: The vertex requires calculation ( $h=-b/2 a$ ) and is not immediately visible. * B: The y-intercept is simply $c$ . (Visible) * C: The direction is determined by the sign of $a$ . (Visible) * D: The stretch is determined by the magnitude of $a$ . (Visible) Choice B is incorrect because $c$ is the y-intercept. Choice C is incorrect because $a$ determines direction. Choice D is incorrect because $a$ determines stretch.

Key Steps:

•

The correct answer is The vertex coordinates

Why others are wrong:

B: Choice B is incorrect and may result from a calculation error.

C: Choice C is incorrect and may result from a calculation error.

D: Choice D is incorrect and may result from a calculation error.

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