Solve Quadratic Equations by Using the Quadratic Formula

Algebra-2

1. Fundamental Concepts

  • Definition: The quadratic formula is used to solve any quadratic equation of the form where .
  • Formula: The solutions to the quadratic equation are given by
  • Discriminant: The discriminant, , determines the nature of the roots:
  • - If , there are two distinct real roots.
  • - If , there is one real root (a repeated root).
  • - If , there are two complex conjugate roots.

2. Key Concepts

Standard Form:
Quadratic Formula:
Application: Used in physics, engineering, and economics to model parabolic motion and other phenomena.

3. Examples

Example 1 (Basic)

Problem: Solve the quadratic equation

Step-by-Step Solution:

  1. Identify coefficients: , ,
  2. Calculate the discriminant:
  3. Apply the quadratic formula:
  4. Solve for : and
Validation: Substitute and into the original equation:
- For :
- For :

Example 2 (Intermediate)

Problem: Solve the quadratic equation

Step-by-Step Solution:

  1. Identify coefficients: , ,
  2. Calculate the discriminant:
  3. Apply the quadratic formula:
  4. Solve for : and
Validation: Substitute and into the original equation:
- For :
- For :

4. Problem-Solving Techniques

  • Identify Coefficients: Clearly identify , , and from the standard form of the quadratic equation.
  • Calculate the Discriminant: Determine the nature of the roots by calculating .
  • Apply the Quadratic Formula: Use the quadratic formula to find the roots, ensuring to handle the sign correctly.
  • Check Solutions: Always substitute the solutions back into the original equation to verify their correctness.