Solve [tex]\(x^2 - 8x = 3\)[/tex] by completing the square. Which is the solution set of the equation?

A. [tex]\(\{4 - \sqrt{19}, 4 + \sqrt{19}\}\)[/tex]
B. [tex]\(\{4 - \sqrt{11}, 4 + \sqrt{11}\}\)[/tex]
C. [tex]\(\{4 - \sqrt{8}, 4 + \sqrt{8}\}\)[/tex]
D. [tex]\(\{4 - \sqrt{3}, 4 + \sqrt{3}\}\)[/tex]



Answer :

To solve the quadratic equation [tex]\( x^2 - 8x = 3 \)[/tex] by completing the square, follow these detailed steps:

1. Rewrite the equation in standard form:
[tex]\[ x^2 - 8x - 3 = 0 \][/tex]

2. Move the constant term to the other side of the equation:
[tex]\[ x^2 - 8x = 3 \][/tex]

3. Complete the square:
- Take half of the coefficient of [tex]\(x\)[/tex], which is [tex]\(-8\)[/tex]:
[tex]\[ \frac{-8}{2} = -4 \][/tex]
- Square it:
[tex]\[ (-4)^2 = 16 \][/tex]
- Add and subtract this square to the left side:
[tex]\[ x^2 - 8x + 16 - 16 = 3 \][/tex]
[tex]\[ (x - 4)^2 - 16 = 3 \][/tex]

4. Isolate the squared term by moving the constant to the other side:
[tex]\[ (x - 4)^2 - 16 = 3 \][/tex]
[tex]\[ (x - 4)^2 = 3 + 16 \][/tex]
[tex]\[ (x - 4)^2 = 19 \][/tex]

5. Take the square root of both sides:
[tex]\[ x - 4 = \pm \sqrt{19} \][/tex]

6. Solve for [tex]\(x\)[/tex]:
[tex]\[ x = 4 \pm \sqrt{19} \][/tex]

Therefore, the solutions to the equation [tex]\( x^2 - 8x = 3 \)[/tex] are [tex]\( 4 - \sqrt{19} \)[/tex] and [tex]\( 4 + \sqrt{19} \)[/tex].

Given the options:
- [tex]\( \{4 - \sqrt{19}, 4 + \sqrt{19}\} \)[/tex]

The solution set is:
[tex]\[ \boxed{\{4 - \sqrt{19}, 4 + \sqrt{19}\}} \][/tex]
The numerical values, rounded appropriately, are approximately [tex]\(-0.3589 \)[/tex] and [tex]\( 8.3589 \)[/tex].