February 16, 2010
Shaw 2008

Shaw 2008

Parabola: The graph of a Quadratic
Equation
6
4
2
- 2
Shaw 2008

 Negative value for a:
The Parabola opens DOWN
 For example
 What is the value for a?
It’s a sad graph
4
2
Shaw 2008
- 2
5

 Positive value for a:
The Parabola opens UP
 For example
 What is the value for a?
It’s a happy graph!
6
4
2
- 2
Shaw 2008

VERTEX
 Where would the Vertex be on these two graphs?
6
4
2
4
2
5
- 2
- 2
Shaw 2008

VERTEX
If a is positive: the vertex is the MINIMUM value of the function.
If a is negative: the vertex is the MAXIMUM value of the function.
 The Vertex always lies on the LINE OF SYMMETRY
Shaw 2008 7

EXAMPLE 1
 What do we know:
 Does this graph open up or down?
 Does the vertex have a MAXIMUM or a
MINIMUM value?
Shaw 2008

EXAMPLE 2
 Does the graph face up or down?
 Is the vertex a Max or Min ?
Shaw 2008 9

Solving Quadratic Equations
 When you are “solving” a quadratic equation you are finding the x-intercepts of the graph
 How many solutions will the equation have?
 Solve the following equation by graphing: y
 x
2 
7 x

10

Solving Quadratic Equations
 Solve the following two equations algebraically
 What variable should we solve for?
y

4 x
2 
16

Solving Quadratic Equations
 Solve the following equations algebraically

HOMEWORK # 14!!!
Solving Quadratic Equations Worksheet
#3-21 multiples of 3
#52, 53, 55
#24-45 multiples of 3, 44, 47
Shaw 2008 13