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Your Notes<br />

Homework<br />

CLASSIFYING CONICS USING THEIR EQUATIONS<br />

Any conic can be described by a general second-degree<br />

equation in x and y:<br />

Ax2 1 Bxy 1 Cy2 1 Dx 1 Ey 1 F 5 0.<br />

The expression B2 2 4AC is the discriminant of the<br />

conic equation and can be used to identify it.<br />

Discriminant Type of Conic<br />

B2 2 4AC 0, B 5 0, and A 5 C Circle<br />

B2 2 4AC 0 and either B Þ 0 or A Þ C Ellipse<br />

B2 2 4AC 0 Parabola<br />

B2 2 4AC 0 Hyperbola<br />

If B<br />

vertical.<br />

0, each axis of the conic is horizontal or<br />

Example 5 Classify a conic<br />

Classify the conic given by<br />

2x 2 1 2y 2 2 5x 1 3y 2 1 5 0.<br />

Solution<br />

Note that A 5 , B 5 , and C 5 , so the value of<br />

the discriminant is: B2 2 4AC 5 5 .<br />

Because B2 2 4AC 0 and A C, the conic is<br />

a .<br />

Checkpoint Classify the conic.<br />

5. 5x 2 2 3y 2 2 10x 2 12y 2 22 5 0<br />

252 Lesson 9.6 Algebra 2 Notetaking Guide Copyright © Holt McDougal. All rights reserved.

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