Solve the quadratic equation $x^2 + 4x + 1 = 0$ by completing the square.

AlgebraQuadratic EquationsCompleting the SquareAlgebraic Manipulation
2025/6/9

1. Problem Description

Solve the quadratic equation x2+4x+1=0x^2 + 4x + 1 = 0 by completing the square.

2. Solution Steps

Step 1: Move the constant term to the right side of the equation.
x2+4x=1x^2 + 4x = -1
Step 2: Complete the square on the left side. Take half of the coefficient of the xx term, square it, and add it to both sides of the equation. The coefficient of the xx term is

4. Half of 4 is 2, and $2^2 = 4$. Add 4 to both sides.

x2+4x+4=1+4x^2 + 4x + 4 = -1 + 4
Step 3: Factor the left side as a perfect square and simplify the right side.
(x+2)2=3(x + 2)^2 = 3
Step 4: Take the square root of both sides.
x+2=±3x + 2 = \pm\sqrt{3}
Step 5: Solve for xx.
x=2±3x = -2 \pm\sqrt{3}

3. Final Answer

x=2+3x = -2 + \sqrt{3} or x=23x = -2 - \sqrt{3}