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Completing the Square in Quadratics

Nov 24, 2024

Solving Quadratic Equations Using Completing the Square

Overview

  • The focus is on solving quadratic equations using the completing the square method.
  • The goal is to rearrange equations in the form of ((x + p)^2 + q).

Key Steps

  1. Rearrange the Equation

    • Start with the quadratic equation and rearrange it into the form ((x + p)^2 + q).
    • This step was covered in a previous video.
  2. Solving for x

    • Example 1: ( (x - 5)^2 - 7 = 0 )
      • Add 7 to both sides: ( (x - 5)^2 = 7 )
      • Square root both sides: ( x - 5 = \pm \sqrt{7} )
      • Add 5 to both sides: ( x = \pm \sqrt{7} + 5 )
      • Solutions:
        • ( x = \sqrt{7} + 5 )
        • ( x = -\sqrt{7} + 5 )
    • Example 2: ( (x + 3)^2 - 1 = 0 )
      • Add 1 to both sides: ( (x + 3)^2 = 1 )
      • Square root both sides: ( x + 3 = \pm 1 )
      • Subtract 3 from both sides: ( x = \pm 1 - 3 )
      • Solutions:
        • ( x = 1 - 3 = -2 )
        • ( x = -1 - 3 = -4 )

Key Points

  • When square rooting, remember to consider both the positive and negative roots.
  • Typically, the process results in two solutions for (x).
  • Solutions can be converted into decimal form using a calculator if specified.

Conclusion

  • Completing the Square Method:

    • Rearrange the quadratic equation into the form ((x + p)^2 + q).
    • Further rearrange to isolate (x) and solve.
    • The technique typically provides two solutions for quadratic equations.
  • The video provides a clear and concise method for solving quadratic equations using the completing the square method.