Set 15: Quadratic Equations

Explanation

Answer: A

Solve: $x^2 + 6x + 9 = 25$

$x = 2, -8$

✓ Correct

$x = 8, -2$

$x = 4, -4$

$x = 5, -5$

Detailed Explanation

Choice A is correct. Choice A is the correct answer. 1. Recognize the left side as a perfect square: $(x + 3)^2 = 25$ . 2. Take the square root: $x + 3 = \pm 5$ . 3. Solve for x: * $x = 5 - 3 = 2$ * $x = -5 - 3 = -8$ Choice B is incorrect because of sign errors. Choice C is incorrect because it ignores the $+3$ . Choice D is incorrect because it ignores the $+3$ .

Key Steps:

•

The correct answer is $x = 2, -8$

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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