Download 9.1 Identifying Quadratic Functions Day 1

March 16, 2015
Get out a Half Sheet of Paper
a) Full First and Last Name
b) What you prefer to be called
c) Write what you do outside of the school day
d) Is there anywhere in particular you need/strongly prefer to sit?
e) How did the first two trimesters of Intermediate Algebra Go?
f) Is there anything you want to know about me?
g) Is there anything else you want me to know about you or that would help me to know about you?
9.1 Identifying
Quadratic Functions
Day 1
9.1 a - I can graph a quadratic function using
a table of values.
9.1 b - I can tell whether a quadratic function
opens up or down given an equation.
March 16, 2015
We have already studied a graph that makes a straight
line, which is called a _________ function.
Equation
y=mx + b
Graph
Now we'll look at... QUADRATIC FUNCTIONS
YELLOW SHEET
Equation
Graph
y=ax2 + bx + c
*must have x to the 2nd power!!
*U shaped curve... called a parabola
March 16, 2015
Tell whether each function is quadratic.
a. y = 5x - 7
b. 7x + y = 4x2
c. x2 + y = x2 + 6x
*Hint:
get y by
itself!
Put this first one on the right side of your YELLOW SHEET.
Graph each quadratic by making a table of values.
1. y = x2 - 3
x
y
March 16, 2015
Graph each quadratic by making a table
of values.
2. y = -2x2 + 1
y
x
In number 7 on tonight's homework, you will use x = -4, -2, 0 2, 4
Graph each quadratic by making a table of values.
3. y = ½x2
x
y
March 16, 2015
Let's look at the three equations that we
graphed. How is the second one different?
y = -2x2 + 1
y = x2 - 3
y = ½x2
YELLOW SHEET NOTES
To determine if a parabola opens up or down...
1.) Write the equation in standard form
y=ax2 + bx + c
2.) Look at the value of a (the number in front of x )
a > 0 (positive)... opens upward
a < 0 (negative)... opens downward
March 16, 2015
YELLOW SHEET EXAMPLE
Tell whether the graph of each quadratic
opens upward or downward. Explain.
1.
2.
3.
4.
A few important vocabulary words...
*vertex: highest or lowest point on a parabola