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Your Notes
Example 1 Graph an equation of a parabola
Graph x 5 1
}
2 y 2 . Identify the focus, directrix, and axis of
symmetry.
1. Rewrite the equation in standard form.
x 5 1
}
2 y 2 Write original equation.
5 Multiply each side by .
2. Identify the focus, directrix, and axis of symmetry. The
equation has the form y2 5 4px where p 5 . The
focus is (p, 0), or 1 , 0 2 . The directrix is x 5 2p, or
x 5 . Because y is squared, the axis of symmetry
is the .
y
3. Draw the parabola by making
a table of values and plotting
1
points. Because p 0, the
parabola opens to the .
1
x
So, use only x-values.
x 1 2 3 4 5
y
Checkpoint Complete the following exercise.
1. Graph y 5 2 1
} x
4 2 . Identify the focus, directrix, and
axis of symmetry.
236 Lesson 9.2 Algebra 2 Notetaking Guide Copyright © Holt McDougal. All rights reserved.
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y
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x