Khan Academy on a Stick
Quadratics functions and equations
In this topic, we'll analyze, graph and solve quadratic equations.

Example 1: Solving a quadratic equation by factoring
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U09_L2_T2_we1 Solving Quadratic Equations by Factoring.avi

Example 2: Solving a quadratic equation by factoring
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U09_L2_T2_we2 Solving Quadratic Equations by Factoring 2.avi

Example 3: Solving a quadratic equation by factoring
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U09_L2_T2_we3 Solving Quadratic Equations by Factoring 3.avi

Example 4: Solving a quadratic equation by factoring
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Applications Problem Factoring Quadratics
Solving quadratics by factoring
Just saying the word "quadratic" will make you feel smart and powerful. Try it. Imagine how smart and powerful you would actually be if you know what a quadratic is. Even better, imagine being able to completely dominate these "quadratics" with new found powers of factorization. Well, dream no longer. This tutorial will be super fun. Just bring to it your equation solving skills, your ability to multiply binomials and a nonlinear way of thinking!

Solving Quadratic Equations by Square Roots
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Solving Quadratic Equations by Square Roots

Example: Solving simple quadratic
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Simple Quadratic Equation

Solving Quadratic Equations by Completing the Square
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Solving Quadratic Equations by Completing the Square

Completing the square (old school)
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Solving a quadratic by completing the square.

Example: Completing perfect square trinomials
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Completing Perfect Square Trinomials

Example 1: Completing the square
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U10_L1_T2_we1 Completing the Square 1

Example 2: Completing the square
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U10_L1_T2_we2 Completing the Square 2

Example 3: Completing the square
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U10_L1_T2_we3 Completing the Square 3

Example 4: Completing the square
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Completing the Square 4

Example 5: Completing the square
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Completing the Square to Solve Quadratic Equations
Completing the square
You're already familiar with factoring quadratics, but have begun to realize that it only is useful in certain cases. Well, this tutorial will introduce you to something far more powerful and general. Even better, it is the bridge to understanding and proving the famous quadratic formula. Welcome to the world of completing the square!

How to use the Quadratic Formula
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Introduction to using the quadratic formula.

Example: Quadratics in standard form
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Quadratic Equations in Standard Form

Proof of Quadratic Formula
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Proof of Quadratic Formula

Example 1: Using the quadratic formula
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Quadratic Formula 1

Example 2: Using the quadratic formula
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Quadratic Formula 2

Example 3: Using the quadratic formula
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Quadratic Formula 3

Example 4: Applying the quadratic formula
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Application Problem with Quadratic Formula

Example 5: Using the quadratic formula
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Applying the Quadratic Formula

Example: Complex roots for a quadratic
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Complex Roots from the Quadratic Formula

Discriminant of Quadratic Equations
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Discriminant of Quadratic Equations

Discriminant for Types of Solutions for a Quadratic
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Discriminant for Types of Solutions for a Quadratic
The quadratic formula (quadratic equation)
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 byproduct 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!

Graphing a parabola with a table of values
Graphing a parabola with a table of values

Parabola vertex and axis of symmetry
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Parabola vertex and axis of symmetry

Graphing a parabola by finding the roots and vertex
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Graphing a parabola by finding the roots and vertex
 Finding the vertex of a parabola example

Multiple examples graphing parabolas using roots and vertices
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Multiple examples graphing parabolas using roots and vertices
 Graphing a parabola using roots and vertex
 Graphing a parabola in vertex form

Parabola Focus and Directrix 1
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Parabola as the locus of all points equidistant from a point and a line

Focus and Directrix of a Parabola 2
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Finding the focus and directrix of a parabola
 Using the focus and directrix to find the equation of a parabola
Graphing quadratics
Tired of lines? Not sure if a parabola is a disease of the gut or a new mode of transportation? Ever wondered what would happen to the graph of a function if you stuck an x² someplace? Well, look no further. In this tutorial, we will study the graphs of quadratic functions (parabolas), including their foci and whatever the plural of directrix is.

Quadratic Inequalities
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Solving quadratic inequalities using factoring

Quadratic Inequalities (Visual Explanation)
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How to solve a quadratic inequality. Visual intuition of what a quadratic inequality means.
Quadratic inequalities
You are familiar with factoring quadratic expressions and solving quadratic equations. Well, as you might guess, not everything in life has to be equal. In this short tutorial we will look at quadratic inequalities.

Solving a quadratic by factoring
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factoring quadratics

CA Algebra I: Factoring Quadratics
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4447, factoring quadratics

Algebra II: Quadratics and Shifts
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3235, Solving quadratics and graph shifts

Examples: Graphing and interpreting quadratics
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3638, shifting quadratic graphs and finding xintercepts (roots)

CA Algebra I: Completing the Square
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4852, completing the square

Introduction to the quadratic equation
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Introduction to using the quadratic equation to solve 2nd degree polynomial equations

Quadratic Equation part 2
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2 more examples of solving equations using the quadratic equation

Quadratic Formula (proof)
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Deriving the quadratic formula by completing the square.

CA Algebra I: Quadratic Equation
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5357, Quadratic Equation

CA Algebra I: Quadratic Roots
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5862, xintercepts of a quadratic function
Quadratic odds and ends
This tutorial has a bunch of extra, but random, videos on quadratics. A completely optional tutorial that you may or may not want to look at. If you do, watch it last. There are some Sal oldies here and some random examples.