Solve the quadratic equation by completing the square. What are the missing pieces to the steps?

[tex]\[
\begin{array}{l}
-27 = 4x^2 - 24x \\
-27 = 4(x^2 - 6x) \\
-27 + \square = 4(x^2 - 6x + 9) \\
9 = 4(x - 3)^2 \\
\frac{9}{4} = (x - 3)^2 \\
\pm \sqrt{\frac{9}{4}} = x - 3 \\
\square = x
\end{array}
\][/tex]

Note: Fill in the missing pieces ([tex]\(\square\)[/tex]) to complete the steps.



Answer :

To solve the quadratic equation [tex]\(-27 = 4x^2 - 24x\)[/tex] by completing the square, let's go through the steps meticulously:

1. Start with the given equation:
[tex]\[ -27 = 4x^2 - 24x \][/tex]

2. Factor out the coefficient of [tex]\(x^2\)[/tex] from the right-hand side:
[tex]\[ -27 = 4 (x^2 - 6x) \][/tex]

3. We need to complete the square inside the parenthesis. To do so, we add and subtract the square of half the coefficient of [tex]\(x\)[/tex]:
[tex]\[ -27 + \square = 4 (x^2 - 6x + 9) \][/tex]

4. The term that was added inside the parenthesis is:
[tex]\[ (6/2)^2 = 9 \][/tex]

Thus, we need to add [tex]\(4 \times 9 = 36\)[/tex] to the left-hand side to keep the equation balanced:
[tex]\[ -27 + 36 = 4 (x^2 - 6x + 9) \][/tex]

So the missing piece is 36.

5. Simplifying the left-hand side, we get:
[tex]\[ 9 = 4 (x - 3)^2 \][/tex]

6. Divide both sides by 4 to isolate the squared term:
[tex]\[ \frac{9}{4} = (x - 3)^2 \][/tex]

7. Take the square root of both sides to solve for [tex]\(x\)[/tex]:
[tex]\[ \pm \sqrt{\frac{9}{4}} = x - 3 \][/tex]

8. Simplify the square root:
[tex]\[ \pm \frac{3}{2} = x - 3 \][/tex]

9. Solving for [tex]\(x\)[/tex], we get two solutions:
[tex]\[ x = 3 + \frac{3}{2} \][/tex]
[tex]\[ x = 3 - \frac{3}{2} \][/tex]

10. Simplifying the expressions, we obtain:
[tex]\[ x = 5.121320343559642 \][/tex]
[tex]\[ x = 0.8786796564403576 \][/tex]

Thus, the missing pieces and solutions are as follows:

- The value added to both sides to complete the square inside the parenthesis is [tex]\(9\)[/tex].
- The solutions to the equation are approximately [tex]\(x = 5.121320343559642\)[/tex] and [tex]\(x = 0.8786796564403576\)[/tex].