March 18, 2014
9.1 Identifying
Quadratic Functions
Day 2
- I can tell whether a quadratic function opens
up or down
- I can identify the vertex and maximum or
minimum of a function
March 18, 2014
Review
1. Tell whether each function is quadratic.
a) y - 2x2 = -2x2 + 4x2
b) y - 3 = 3x + 4
2. Graph the quadratic function y = 3x2 - 4
3. Tell whether the quadratic function opens up or down
a) y = -3 - 2x + 5x2
b) y + 2x2 = 5x - 1
March 18, 2014
A few important vocabulary words...
*vertex: highest or lowest point on a parabola
*maximum value: y-coordinate of vertex for parabola
that opens down
*minimum value: y-coordinate of vertex for parabola
that opens up
March 18, 2014
Identify the vertex of each parabola.
Then give the minimum or maximum
value of the function.
4.
5.
March 18, 2014
Identify the vertex of each parabola.
Then give the minimum or maximum
value of the function.
6.
7.
••
•
March 18, 2014
Vocabulary Reminders:
Domain: all possible __ values
Range: all possible __ values
To determine domain for a
quadratic function think
about what you can plug in
for x...
anything you want!
x
For a Quadratic Function:
The Domain is All Real Numbers
*Range takes a little more thinking
y
March 18, 2014
Range is all the possible y values...
Questions to ask yourself
to find Range:
1. Does this have a
minimum or maximum?
(What is it?)
2. Since it is a M_______,
all the y values are
_____ _____ that value.
3. So... Range:
March 18, 2014
Find the Domain and Range.
D:
R:
March 18, 2014
Find the Domain and Range.
D:
R:
D:
R:
Range:
1. Does this have a minimum or
maximum? (What is it?)
2. Since it is a M_______, all the
y values are ______ that value.
3. So... R:
March 18, 2014
Let's put it all together...
1. Graph y = -x2 + 2
2. Does it open
upward or downward?
(How can you tell from the equation? How can you tell
from the graph?)
3. Identify the vertex, tell
whether it is a max or min,
and give max or min value.
4. Give the domain and range.
x
y
March 18, 2014