1. ALGEBRA I - SECTION 9-2 (Quadratic Functions)
12/3/2018
ALGEBRA I @
SECTION 9-2 : QUADRATIC FUNCTIONS

2. Questions whose answers you should know.
Given the quadratic equation y = ax2 + bx + c ….
1) How does “a” effect the graph?
a > 0 graph opens up larger “a” is, the narrower the graph (stretched)
a < 0 graph opens down smaller “a” is, the broader the graph (compressed)
2) How does “c” effect the graph?
+ c shifts the graph up “c” units
- c shifts the graph down “c” units

3. On to that thing called the internet :
3) How does “b” effect the graph?
Hint : Look at the bottom of page 553 of your book for the answer.
On to that thing called the internet :

4. y = x2 + 3x y = x2 – 3x y = -x2 – 2 y = -x2 + 2 ANSWERS : 3 – D 5 - C
Match each function with its graph.
A C
B D
y = x2 + 3x
y = x2 – 3x
y = -x2 – 2
y = -x2 + 2
ANSWERS :
3 – D 5 - C
4 – A 6 - B

5. Find the coordinates of the vertex and the equation of the axis of symmetry for each equation.
7) y = 2x2 – 8x
8) y = -3x2 + 6x - 1
Vertex : (2, -8)
Axis of Symmetry : x = 2
Vertex : (1, 2)
Axis of Symmetry : x = 1

6. y = -2x2 + 8x - 4 vertex : AOS : (2, 4) x = 2
9) Graph the function. Label the vertex and axis of symmetry.
y = -2x2 + 8x - 4
vertex :
AOS :
(2, 4)
x = 2