2

Set 7: Quadratic Equations (Advanced)

Explanation

Answer: A

Which equation has an axis of symmetry at x=3x = 3?

A.

y=x2−6x+5y = x^2 - 6x + 5

✓ Correct
B.

y=x2+6x+5y = x^2 + 6x + 5

C.

y=x2−3x+5y = x^2 - 3x + 5

D.

y=2x2−6x+5y = 2x^2 - 6x + 5

Detailed Explanation

Choice A is correct. Choice A is the correct answer. We check x=−b/2ax = -b/2 a for each option. * A: −(−6)/2(1)=6/2=3-(-6) / 2(1) = 6/2 = 3. (Correct) * B: −6/2(1)=−3-6 / 2(1) = -3. * C: −(−3)/2(1)=1.5-(-3) / 2(1) = 1.5. * D: −(−6)/2(2)=6/4=1.5-(-6) / 2(2) = 6/4 = 1.5. Choice B is incorrect because axis is x=−3x=-3. Choice C is incorrect because axis is x=1.5x=1.5. Choice D is incorrect because axis is x=1.5x=1.5.

Key Steps:

•

The correct answer is y=x2−6x+5y = x^2 - 6x + 5

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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