How can I solve the equation x² – 24x + 80 by completing the square, and what is the solution set?

Solving the Equation x² – 24x + 80 by Completing the Square

To solve the quadratic equation x² – 24x + 80 = 0 by completing the square, follow these steps:

  1. Rearrange the equation: Start with the original equation:
    x² - 24x + 80 = 0
  2. Move the constant term (80) to the other side:
    x² - 24x = -80
  3. Determine the value to complete the square: Take half of the coefficient of x (which is -24), square it, and add it to both sides:
                    Half of -24 is -12.
                    Squaring -12 gives 144.
                
  4. Add 144 to both sides:
    x² - 24x + 144 = -80 + 144

    This simplifies to:

    x² - 24x + 144 = 64
  5. Factor the left-hand side:
    (x - 12)² = 64
  6. Take the square root of both sides:
    x - 12 = ±8
  7. Solve for x:
    • For x – 12 = 8:
      x = 8 + 12 = 20
    • For x – 12 = -8:
      x = -8 + 12 = 4

Conclusion

The solution set of the equation x² – 24x + 80 = 0 is:

{4, 20}

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