1. Before: March 15, 2018
Tell whether the graph of each quadratic function opens upward or downward. Explain.
y = 7x² - 4x
x – 3x² + y = 5
y = -2/3x²

2. During: Characteristics of Quadratic Functions

3. Recall that an x-intercept of a function is a value of x when y = 0.
A zero of a function is an x-value that makes the function equal to 0. So a zero of a function is the same as an x-intercept of a function.
Since a graph intersects the x-axis at the point or points containing an x-intercept these intersections are also at the zeros of the function. A quadratic function may have one, two, or no zeros.

4. “We Do” Finding Zeros of Quadratic Functions From Graphs
Find the zeros of each quadratic function from its graph. Check your answer.

5. “We Do” Finding Zeros of Quadratic Functions From Graphs
Find the zeros of each quadratic function from its graph. Check your answer.

6. “We Do” Finding Zeros of Quadratic Functions From Graphs
Find the zeros of each quadratic function from its graph. Check your answer.

7. “You Do” Finding Zeros of Quadratic Functions From Graphs
Find the zeros of each quadratic function from its graph. Check your answer.

8. “You Do” Finding Zeros of Quadratic Functions From Graphs
Find the zeros of each quadratic function from its graph. Check your answer.

9. A vertical line that divides a parabola into two symmetrical halves is the axis of symmetry. The axis of symmetry always passes through the vertex of the parabola. You can use the zeros to find the axis of symmetry.

10. “We Do” Finding the Axis of Symmetry by Using Zeros
Find the axis of symmetry of each parabola.

11. “We Do” Finding the Axis of Symmetry by Using Zeros
Find the axis of symmetry of each parabola.

12. “You Do” Finding the Axis of Symmetry by Using Zeros
Find the axis of symmetry of each parabola.

13. “You Do” Finding the Axis of Symmetry by Using Zeros
Find the axis of symmetry of each parabola.

14. Finding the Axis of Symmetry by Using the Formula
Example
For a quadratic function y = ax² + bx + c, the axis of symmetry is the vertical line:
x = -b 2a
y = 2x² + 4x + 5

15. “I Do” Finding the Axis of Symmetry by Using the Formula
Find the axis of symmetry of the graph of
y = x² + 3x + 4.

16. “We Do” Finding the Axis of Symmetry by Using the Formula
Find the axis of symmetry of the graph of
y = 2x² + x + 3.

17. “You Do” Finding the Axis of Symmetry by Using the Formula
Find the axis of symmetry of the graph of
y = -3x² + 10x + 9.

18. Finding the Vertex of a Parabola
Once you have found the axis of symmetry, you can use it to identify the vertex.
Finding the Vertex of a Parabola
Step 1: To find the x-coordinate of the vertex, find the axis of symmetry by using zeros or the formula.
Step 2: To find the corresponding y-coordinate, substitute the x-coordinate of the vertex into the function.
Step 3: Write the vertex as an ordered pair.

19. “We Do” Finding the Vertex of a Parabola
Find the vertex.
y = -3x² + 6x - 7

20. “You Do” Finding the Vertex of a Parabola
Find the vertex.
y = x² - 4x - 10

21. Homework
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