8
advanced-math

Solve: x2+6x+9=25x^2 + 6x + 9 = 25

A

x=2,−8x = 2, -8

B

x=8,−2x = 8, -2

C

x=4,−4x = 4, -4

D

x=5,−5x = 5, -5

Correct Answer: A

Choice A is the correct answer.

  1. Recognize the left side as a perfect square: (x+3)2=25(x + 3)^2 = 25.
  2. Take the square root: x+3=±5x + 3 = \pm 5.
  3. Solve for x:
    • x=5−3=2x = 5 - 3 = 2
    • x=−5−3=−8x = -5 - 3 = -8

Choice B is incorrect because of sign errors. Choice C is incorrect because it ignores the +3+3. Choice D is incorrect because it ignores the +3+3.

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Set 5: Quadratic Equations and Functions 5