CK-12 Foundation
Ck 12: Algebra: The Quadratic Formula: Deriving and Using the Quadratic Formula
[Free Registration/Login may be required to access all resource tools.] This lesson covers deriving the quadratic formula and using it to solve any quadratic equation.
Math Medics
S.o.s. Math: Quadratic Formula: Completing the Square
This tutorial explains the quadratic formula by reviewing its origin from the process of completing the square. Includes examples and a few exercises.
Wyzant
Wyzant: Solving Using the Quadratic Formula Worksheet
The practice sheet reviews how to solve equations using the quadratic formula. The resource consists of 20 questions with answers available.
Lawrence Hall of Science
The Math Page: Skill in Algebra: Quadratic Equations
Here is a site that clearly and thoroughly explains the quadratic equations, including how to solve them by factoring, completing the square, and using the quadratic formula. There are example problems solved, problems for the student to...
Khan Academy
Khan Academy: Solve Quadratic Equations: Complex Solutions
Solve quadratic equations using the quadratic formula. Some of the equations have real solutions while others have complex solutions.
Illustrative Mathematics
Illustrative Mathematics: A sse.b.3: Profit of a Company
This task compares the usefulness of different forms of a quadratic expression. Students have to choose which form most easily provides information about the maximum value. Aligns with A-SSE.B.3.
Purple Math
Purplemath: Special Factoring: Differences of Squares
Demonstrates how to use the formula for finding the differences of squares, and warns against trying to factor a sum of squares.
Purple Math
Purplemath: Solving Polynomials: How To
Demonstrates the steps involved in solving a general polynomial, including how to use the Rational Roots Test and synthetic division. Points out when using a graphing calculator can be very helpful.