Solve by completing the square: x^2 + 4x - 5 = 0.

• A. x = 1 or x = -5
• B. x = -1 or x = 5
• C. x = 0 or x = -4
• D. x = 2 or x = -6

Answer: (A)

Completing the square turns the left side into a perfect square so you can solve by taking a square root. Move the constant: x^2 + 4x = 5. Add (4/2)^2 = 4 to both sides to form a square: (x + 2)^2 = 9. Take the square root: x + 2 = ±3, which gives x = 1 or x = -5. These values satisfy the equation when checked. The other options don’t solve the equation; for example, x = -1 gives 1 - 4 - 5 = -8, not zero.