15 Quadratic Equations

Quad means square in Latin. A quadratic equation is polynomial where the highest order term is a square; it is thus said to be a second order polynomial. Quadratic equations are very important for two reasons: 1) They can represent a wide variety of things like motion in the real world, and 2) We can find solutions for them. While there is a general formula for solving quadratic equations, it requires a good deal of calculation and taking square roots. Therefore, we look for tricks, special cases that are easier to solve.

15.1 Solving Quadratic Equations

- Solve quadratic equations by factoring.
- Set quadratics equal to zero.
- Solve quadratics by taking the square root of both sides of the equation.
- Determine if a solution is a real or complex number.

  • Solving by Factoring

  • Solving with Square Roots

15.2 Solving by Completing the Square

- Recognize the perfect square pattern for trinomials.
- Factor perfect square trinomials.
- Complete the square on a trinomial.
- Solve quadratic equations by completing the square.

  • Factoring Perfect Squares

  • Completing the Square

  • Solving by Completing the Square

15.3 Graphing Quadratic Equations

- Know how the constants a, b, and c change the shape of a parabola.
- Determine equation for the axis of symmetry of the parabola.
- Find the real roots of a parabola from the equation.
- Find the vertex of a parabola from the formula.

  • Coefficients of Quadratic Equations

  • x-Intercepts

  • Vertex Form y=a(x-h)^2+k

15.4 The Quadratic Formula

- Solves quadratic equations using the quadratic formula.
- Applies the discriminant to determine the number of real and complex roots.

  • Solving with the Quadratic Formula

15.5 Additional Assignments

- Applies knowledge of parabolas to motion problems.
- Visualizes complex roots graphically.

  • Baseball & Parabolic Motion

  • Seeing Complex Roots of Quadratics

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Topics

1 Whole Numbers
2 Fractions
3 Decimals
4 Ratio & Proportion
5 Tables & Graphs
6 The Real Numbers
7 Solving Linear Equations
8 Graphing Linear Equations
9 Systems of Equations
10 Geometry
11 Polynomials
12 Factoring
13 Rational Expressions & Equations
14 Exponents & Radicals
15 Quadratic Equations
16 Introduction to Functions
19 Exponential and Logarithmic Functions