7
advanced-math

Find the axis of symmetry for y=−2x2+8x−1y = -2x^2 + 8x - 1.

A

x=2x = 2

B

x=−2x = -2

C

x=4x = 4

D

x=−4x = -4

Correct Answer: A

Choice A is the correct answer. The axis of symmetry for a parabola y=ax2+bx+cy = ax^2 + bx + c is the vertical line x=−b/2ax = -b/2a.

  1. Identify: a=−2,b=8a = -2, b = 8.
  2. Substitute: x=−8/(2(−2))x = -8 / (2(-2)).
  3. Simplify: x=−8/−4=2x = -8 / -4 = 2.

Choice B is incorrect because of a sign error. Choice C is incorrect because it forgets the 2 in the denominator. Choice D is incorrect because of both errors.

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Set 5: Quadratic Equations and Functions 5