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The quadratic formula (quadratic equation)

1 article
8 videos
1 skill
Probably one of the most famous tools in mathematics, the quadratic formula (a.k.a. quadratic equation) helps you think about the roots of ANY quadratic (even ones that have no real roots)! As you'll see, it is just the by-product of completing the square, but understanding and applying the formula will take your algebra skills to new heights. In theory, one could apply the quadratic formula in a brainless way without understanding factoring or completing the square, but that's lame and uninteresting. We recommend coming to this tutorial with a solid background in both of those techniques. Have fun!

How to use the quadratic formula

VIDEO 16:32 minutes
Introduction to using the quadratic formula.

Example: Quadratics in standard form

VIDEO 2:21 minutes
Quadratic Equations in Standard Form

Proof of quadratic formula

VIDEO 7:44 minutes
Proof of Quadratic Formula

Example 1: Using the quadratic formula

VIDEO 5:34 minutes
Quadratic Formula 1

Example 2: Using the quadratic formula

VIDEO 6:40 minutes
Quadratic Formula 2

Example 3: Using the quadratic formula

VIDEO 4:59 minutes
Quadratic Formula 3

Example 4: Applying the quadratic formula

VIDEO 5:53 minutes
Application Problem with Quadratic Formula

Example 5: Using the quadratic formula

VIDEO 4:51 minutes
Applying the Quadratic Formula

Using the quadratic formula

PRACTICE PROBLEMS
Use the quadratic formula to find the roots of a quadratic function.