1. Graphing Quadratics of ax2 +bx + c
Section 10 – 2 Day 2
Graphing Quadratics of
ax2 +bx + c

2. Graphing Quadratics
Step 1 – Determine whether parabola opens UP or DOWN: a > 0 = UP & a < 0 = DOWN
Step 2: Find and plot vertex/axis of symmetry:
Use for your x-value then substituting into the equation to find your y-value.
Step 3: Make a TABLE and plot points – Good idea to pick 2 points GREATER than and 2 points LESS than x-coordinate of vertex. Plug into equation to find y-values 2

3. Graphing Quadratics cont.
REMEMBER – A parabola is SYMMETRIC!!
Hint: if “a” term is a fraction. Choose points that are MULTIPLES of the DENOMINATOR!
Step 4: Draw a PARABOLA connecting points. 3

4. Parabola: Vertex: a = 1 b = -4 c = 3 Example 1 Graph: y = x2 – 4x + 3

5. Table: Example 1 cont. x (domain) y (range) y = x2 – 4x + 3
y = (0)2 – 4(0) + 3 3
y = (1)2 – 4(1) + 3 1
y = (2)2 – 4(2) + 3 -1
Vertex-> 2
y = (3)2 – 4(3) + 3 3
y = (4)2 – 4(4) + 3 3 4 5

6. Parabola: Vertex: a = -2 b = -8 c = -3 Example 2
Graph: y = – 2x2 – 8x – 3
Parabola:
Vertex:
a = -2
b = -8
c = -3 6

7. Table: Example 2 cont. x (domain) y (range) y = -2x2 – 8x – 3 -4-3
y = -2(-3)2 – 8(-3) – 3 3 -3
y = -2(-2)2 – 8(-2) – 3 5
Vertex-> -2
y = -2(-1)2 – 8(-1) – 3 3 -1
y = -2(-4)2 – 8(-4) – 3 -3 7

8. Example 3
Graph:
Parabola:
Vertex:
a = 1/2
b = 0
c = 4 8

9. Table: Example 2 cont. x (domain) y (range) y = ½ x2 + 4 -412
y = ½ (-2)2 + 4 6 -2
y = ½ (0)2 + 4 4
Vertex->
y = ½ (2)2 + 4 6 2
y = ½ (4)2 + 4 12 4 9

10. Homework
Section 10-2 Day 2
Worksheet