Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
8. Conic Sections
Parabolas
4:01 minutes
Problem 43
Textbook Question
Textbook QuestionIn Exercises 43–48, convert each equation to standard form by completing the square on x or y. Then find the vertex, focus, and directrix of the parabola. Finally, graph the parabola. x^2 - 2x - 4y + 9 =0
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Completing the Square
Completing the square is a method used to transform a quadratic equation into a perfect square trinomial. This technique allows us to rewrite the equation in a form that makes it easier to identify key features of the parabola, such as its vertex. By rearranging the equation and adjusting constants, we can express it in standard form, which is essential for further analysis.
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Standard Form of a Parabola
The standard form of a parabola is typically expressed as (x - h)² = 4p(y - k) for vertical parabolas or (y - k)² = 4p(x - h) for horizontal parabolas. Here, (h, k) represents the vertex of the parabola, and 'p' indicates the distance from the vertex to the focus and the directrix. Understanding this form is crucial for identifying the parabola's geometric properties.
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Parabolas as Conic Sections
Vertex, Focus, and Directrix
The vertex of a parabola is the highest or lowest point, depending on its orientation. The focus is a point located along the axis of symmetry, where all lines drawn parallel to the axis reflect off the parabola. The directrix is a line perpendicular to the axis of symmetry, equidistant from the vertex as the focus. Together, these elements define the parabola's shape and position in the coordinate plane.
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