1. y = x 2 – 2x – 8 xy Vertex? Max or Min? Axis of Symmetry? Do Now (#4 from classwork)

2. A parabolic mirror at the Seattle Science Museum.

3. Roots of a Parabola A point where a parabola crosses the x-axis is called a root of the parabola (where y = 0). Parabolas can have two roots, one root, or no roots.

4. Lets Look at this equation:y = x 2 – 4x – 5 a = 1b = -4 c = 5 Since a is positive the graph opens up. Vertex is at 4/2 or x = 2 y = x 2 – 4x – 5 xy What are the roots of this parabola?

5. Let’s see what happens if we set the last equation equal to zero: y = x 2 - 4x - 5 0 = x 2 - 4x - 5

6. Lets Look at this equation:y = -x 2 + 6x – 5 a = -1 b = 6 c = -5Vertex is at -6/-2 or x = 3 y = -x 2 + 6x – 5 xy What are the roots of this parabola?

7. Check by factoring:

9. Graphing Using the Calculator When creating a table for a parabola, you always need to find the vertex first. Instead of using the formula, you can find the vertex using the table in your calculator. Looking only at the y-values, you need to find the point where the y-values start to repeat.

10. y = x 2 + 2x – 8 xy Vertex? Max or Min? Axis of Symmetry? Roots? y = x 2 + 2x – 8

11. Use a table of values to graph Answer: xy

12. Use a table of values to graph Answer: xy

13. Use a table of values to graph xy

14. Homework Graphing Parabolas Homework #2