#### Answer

horizontal; vertical

#### Work Step by Step

The equation $y=4$ is a horizontal line (any $y=c$ graph is a horizontal line).
The equation $x=4$ is a vertical line (any $x=c$ graph is a vertical line).

Published by
Pearson

ISBN 10:
0321969359

ISBN 13:
978-0-32196-935-4

horizontal; vertical

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