Solve x² - 6x = 8 by completing the Square.

Algebra and Trigonometry (6th Edition)
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ISBN:9780134463216
Author:Robert F. Blitzer
Publisher:Robert F. Blitzer
ChapterP: Prerequisites: Fundamental Concepts Of Algebra
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Problem 1MCCP: In Exercises 1-25, simplify the given expression or perform the indicated operation (and simplify,...
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Please solve by using completing the square method thank you!

### Problem 16: Solving Quadratic Equations by Completing the Square

**Objective:**
Solve the equation \( x^2 - 6x = 8 \) by completing the square.

**Steps for Completing the Square:**

1. **Original Equation:** 
   \[
   x^2 - 6x = 8
   \]

2. **Move the Constant Term to the Other Side:**
   \[
   x^2 - 6x - 8 = 0
   \]

3. **Add and Subtract the Square of Half the Coefficient of \(x\):**

   - Take half of the coefficient of \(x\) (which is -6), square it, and add and subtract this value inside the equation.
   - Half of -6 is -3, and \((-3)^2 = 9\).

4. **Rewrite the Equation:**
   \[
   x^2 - 6x + 9 = 8 + 9
   \]

5. **Simplify Both Sides:**
   \[
   (x-3)^2 = 17
   \]

6. **Solve for \(x\):**
   - Take the square root of both sides:
     \[
     x - 3 = \pm \sqrt{17}
     \]
   - Solve for \(x\):
     \[
     x = 3 \pm \sqrt{17}
     \]

**Conclusion:**
The solutions for the equation \( x^2 - 6x = 8 \) are \( x = 3 + \sqrt{17} \) and \( x = 3 - \sqrt{17} \).

**Explanation:** 

Completing the square involves turning a quadratic expression into a perfect square trinomial. This process makes it easier to solve quadratics that are not easily factorable, providing a pathway to finding solutions by using the square root method.
Transcribed Image Text:### Problem 16: Solving Quadratic Equations by Completing the Square **Objective:** Solve the equation \( x^2 - 6x = 8 \) by completing the square. **Steps for Completing the Square:** 1. **Original Equation:** \[ x^2 - 6x = 8 \] 2. **Move the Constant Term to the Other Side:** \[ x^2 - 6x - 8 = 0 \] 3. **Add and Subtract the Square of Half the Coefficient of \(x\):** - Take half of the coefficient of \(x\) (which is -6), square it, and add and subtract this value inside the equation. - Half of -6 is -3, and \((-3)^2 = 9\). 4. **Rewrite the Equation:** \[ x^2 - 6x + 9 = 8 + 9 \] 5. **Simplify Both Sides:** \[ (x-3)^2 = 17 \] 6. **Solve for \(x\):** - Take the square root of both sides: \[ x - 3 = \pm \sqrt{17} \] - Solve for \(x\): \[ x = 3 \pm \sqrt{17} \] **Conclusion:** The solutions for the equation \( x^2 - 6x = 8 \) are \( x = 3 + \sqrt{17} \) and \( x = 3 - \sqrt{17} \). **Explanation:** Completing the square involves turning a quadratic expression into a perfect square trinomial. This process makes it easier to solve quadratics that are not easily factorable, providing a pathway to finding solutions by using the square root method.
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