Introduction to Quadratic Equations
- Definition: A quadratic equation is a polynomial equation of the form ( ax^2 + bx + c = 0 ), where ( a \neq 0 ).
- Characteristics: The highest degree of the variable ( x ) is 2, and the graph of a quadratic equation is a parabola.
- Applications: Used in various fields such as physics (projectile motion), engineering (designs), and finance (profit analysis).
Standard Form of a Quadratic Equation
- The standard form: ( ax^2 + bx + c = 0 )
- Coefficients:
- ( a ) (leading coefficient): determines the direction of the parabola (opens upward if ( a > 0 ) and downward if ( a < 0 )).
- ( b ): affects the position of the vertex on the x-axis.
- ( c ): the y-intercept of the parabola.
- Example: Consider ( 2x^2 - 4x + 1 = 0 ).
Factoring Quadratic Equations
- Definition: Expressing ( ax^2 + bx + c ) as ( (px + q)(rx + s) = 0 ).
- Steps:
- Set the equation to zero.
- Find two numbers that multiply to ( ac ) and add to ( b ).
- Rewrite and factor the equation.
- Example: Factor ( x^2 - 5x + 6 = 0 ) into ( (x - 2)(x - 3) = 0 ).
Using the Quadratic Formula
- The Quadratic Formula: ( x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} )
- Steps to use:
- Identify coefficients ( a, b, ) and ( c ).
- Calculate the discriminant ( D = b^2 - 4ac ).
- If ( D > 0 ): two distinct real roots.
- If ( D = 0 ): one real root.
- If ( D < 0 ): no real roots.
- Example: For ( 3x^2 + 6x + 3 = 0 ), apply the formula.
Graphing Quadratic Functions
- Key features of the graph:
- Vertex: The highest or lowest point of the parabola.
- Axis of symmetry: A vertical line that divides the parabola into two mirror images.
- Intercepts: Points where the graph crosses the axes (x-intercepts and y-intercept).
- Example: Graphing ( y = x^2 - 4x + 3 ).
{The image of a graph showing the parabola of the equation ( y = x^2 - 4x + 3 ), highlighting the vertex, axis of symmetry, and x-intercepts.}
Real-World Applications of Quadratic Equations
- Physics: Modeling the trajectory of thrown objects.
- Business: Optimization problems, like maximizing profit given constraints.
- Engineering: Calculating the dimensions of physical structures or materials.
- Example: A water fountain designs using quadratic equations to ensure a proper arc.
{The image of a water fountain demonstrating the arc of the water, shaped like a parabola, with a quadratic equation illustrated nearby.}
Review and Practice Problems
- Recap key concepts:
- Definition and standard form of quadratic equations.
- Methods to solve (factoring, quadratic formula).
- Graphing techniques and key features.
- Practice problems:
- Solve ( x^2 - 7x + 10 = 0 ) by factoring.
- Graph ( y = -2x^2 + 8x - 5 ) and identify the vertex and intercepts.
- Use the quadratic formula to find the roots of ( 2x^2 + 8x + 6 = 0 ).
{The image of a blackboard filled with practice problems about quadratic equations, with various solutions written down to illustrate solving methods.}