In this lesson, you learned how to:

• Explain the steps and complete some missing steps for deriving the quadratic formula.
• Explain how the quadratic formula is related to the process of completing the square for a quadratic equation $a{x}^2+bx+c=0$.

Here are the activities that helped you reach those goals:

• 9.8.1: Deriving the Quadratic Formula, Part 1
  • In this activity, you learned how to derive the quadratic formula by completing the square for a quadratic equation without evaluating some of the numerical expressions along the way.
  • 9.8.1: Self Check
  • 9.8.1: Additional Resources
• 9.8.2: Deriving the Quadratic Formula, Part 2
  • In this activity, you studied a series of steps to solve $a{x}^2+bx+c=0$ by completing the square and making sense of how it leads to the quadratic formula.
  • 9.8.2: Self Check
  • 9.8.2: Additional Resources
• 9.8.3: Understanding That the Quadratic Formula Is the Combined Steps of Completing the Square
  • In this activity, you had to explain parts of a solution for solving an equation by completing the square, where each step was shown, but numerical expressions were not evaluated.

After these activities, you completed the following practice:

• 9.8.4: Practice