8

Set 10: Quadratic Equations

Explanation

Answer: A

What is the minimum value of y=x2+4x−1y = x^2 + 4x - 1?

A.

-5

✓ Correct
B.

-1

C.

-2

D.

3

Detailed Explanation

Choice A is correct. Choice A is the correct answer. The minimum value is the y-coordinate of the vertex. 1. Find x-coordinate: x=−4/2(1)=−2x = -4 / 2(1) = -2. 2. Substitute x=−2x = -2: y=(−2)2+4(−2)−1y = (-2)^2 + 4(-2) - 1. 3. Calculate: y=4−8−1=−5y = 4 - 8 - 1 = -5. Choice B is incorrect because it is the y-intercept. Choice C is incorrect because it is the x-coordinate. Choice D is incorrect because of calculation errors.

Key Steps:

•

The correct answer is -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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