HyperBola
Example 7 Graph
Solution
This is a hyperbola.
There are actually two standard forms for a hyperbola. Here are the basics for each form.
Form
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Center
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(h, k)
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(h, k)
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Opens
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Opens right and left
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Opens up and down
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Vertices
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a units right
and left
of center.
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b units up and
down
from center.
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Slope of Asymptotes
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So, what does all this mean? First, notice that one of the terms is
positive and the other is negative.
This will determine which direction the two parts of the hyperbola
open. If the x term is positive the hyperbola opens left and right. Likewise, if the y term is positive the parabola opens up and down.
Both have the same “center”. Note that hyperbolas don’t really have a
center in the sense that circles and ellipses have centers. The center is the starting point in
graphing a hyperbola. It tells us how
to get to the vertices and how to get the asymptotes set up.
The asymptotes of a hyperbola are two lines that intersect
at the center and have the slopes listed above. As you move farther out from the center the
graph will get closer and closer to the asymptotes.
For the equation listed here the hyperbola will open left
and right. Its center is
(-1, 2). The two
vertices are (-4, 2) and (2, 2). The
asymptotes will have slopes .
Here is a sketch of this hyperbola. Note that the asymptotes are denoted by the
two dashed lines.
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