Page 48 - Math Course 3 (Book 1)

Quadratic Equations

Vertex and Axis of Symmetry
Match Equations and Graphs
2
Consider the graph of y = 3x – 6x + 1.
Examples Identify the vertex as a maximum or minimum.

A. minimum
B. maximum
Read the Test Item C. neither
You are given a quadratic function, and you are D. cannot be determined
asked to choose its graph.

Solve the Test Item Answer
Find the axis of symmetry of the graph
2
y = –x – 2x – 2. Consider the graph of y = 3x – 6x + 1.
2
Graph the function.
b Equation for the axis of A.
x = – B.
2a symmetry.
–2
x = – 2(–1) or –1 a = –1 and b = –2

The axis of symmetry is –1. Look at the graphs.
Since only choices C and D have x = –1 as their
axis of symmetry, you can eliminate choices A and C. D.
2
B. Since the coefficient of the x term is negative,
the graph opens downward. Eliminate choice C.

Answer D

Your Turn! Answer

Vertex and Axis of Symmetry Match Equations and Graphs

2
2
Consider the graph of y = 3x – 6x + 1. Write the Which is the graph of y = –x + 2x?
equation of the axis of symmetry.
A. B.
A. x = –6
B. x = 6
C. x = –1
D. x = 1

Answer
C. D.

Consider the graph of y = 3x – 6x + 1.
2
Find the coordinates of the vertex.

A. (–1, 10)
B. (1, –2)
C. (0, 1)
D. (–1, –8)

Answer Answer
40