Graphs of Quadratic Functions

7.11.5 Graphs of Quadratic Functions

7.11.5 • Graphs of Quadratic Functions

The function $f$ is given by $f (x) = (x - 2) (x + 4)$ .

Without using graphing technology, answer questions 1 – 4.

What are the $x$ -intercepts of the graph representing $f$ ?

Compare your answer:

$x$ -intercepts for function $f$ : $(2, 0)$ and $(- 4, 0)$

What is the $x$ -coordinate of the vertex of the graph?

-1

What is the $y$ -coordinate of the vertex of the graph?

-9

What is the $y$ -intercept?

Compare your answer:

The $y$ -intercept is $(0, - 8)$ , because $(0 - 2) (0 + 4) = (- 2) (4) = - 8$ .

Use the graphing tool or technology outside the course. Sketch a graph that represents $f$ .

Compare your answer:

The graph opens upward with vertex at $(- 1, - 9)$ and $x$ -intercepts at $(2, 0)$ and $(- 4, 0)$ .