Use completing the square to solve this quadratic equation.

[tex]\[ x^2 + 6x + 9 = 2 \][/tex]

Check all that apply.

A. [tex]\( x = -3 - \sqrt{2} \)[/tex]
B. [tex]\( x = 3 - \sqrt{2} \)[/tex]
C. [tex]\( x = -3 + \sqrt{2} \)[/tex]
D. [tex]\( x = 3 + \sqrt{2} \)[/tex]



Answer :

To solve the quadratic equation using the method of completing the square, follow these detailed steps:

1. Start with the original equation:
[tex]\[ x^2 + 6x + 9 = 2 \][/tex]

2. Move the constant term on the left side to the right side of the equation:
[tex]\[ x^2 + 6x + 9 - 2 = 0 \][/tex]
[tex]\[ x^2 + 6x + 7 = 0 \][/tex]

3. Complete the square:
- Take the coefficient of [tex]\(x\)[/tex], which is 6, divide it by 2, and then square it:
[tex]\[ \left(\frac{6}{2}\right)^2 = 3^2 = 9 \][/tex]
- Add and subtract this square inside the equation:
[tex]\[ x^2 + 6x + 9 - 9 + 7 = 0 \][/tex]
- Reformat the left side as a squared term and combine constants on the right side:
[tex]\[ (x + 3)^2 - 2 = 0 \][/tex]

4. Isolate the squared term:
[tex]\[ (x + 3)^2 = 2 \][/tex]

5. Take the square root of both sides:
[tex]\[ x + 3 = \pm\sqrt{2} \][/tex]

6. Solve for [tex]\(x\)[/tex]:
- For the positive square root:
[tex]\[ x + 3 = \sqrt{2} \][/tex]
[tex]\[ x = \sqrt{2} - 3 \][/tex]
Which simplifies to:
[tex]\[ x = -3 + \sqrt{2} \][/tex]
- For the negative square root:
[tex]\[ x + 3 = -\sqrt{2} \][/tex]
[tex]\[ x = -\sqrt{2} - 3 \][/tex]
Which simplifies to:
[tex]\[ x = -3 - \sqrt{2} \][/tex]

So, the solutions to the quadratic equation [tex]\(x^2 + 6x + 9 = 2\)[/tex] are:

[tex]\[ x = -3 + \sqrt{2} \quad \text{and} \quad x = -3 - \sqrt{2} \][/tex]

Hence, the correct answers are:
- [tex]\(x = -3 - \sqrt{2}\)[/tex] (Option A)
- [tex]\(x = -3 + \sqrt{2}\)[/tex] (Option C)