Find the vertex, focus, and directrix of each parabola with the given equation. Then graph the parabola. (y + 1)2 = - 8x
Ch. 7 - Conic Sections

Chapter 8, Problem 41
Graph each ellipse and give the location of its foci. (x − 4)²/9 + (y +2)² /25= 1
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Identify the standard form of the ellipse equation: \(\frac{(x - h)^2}{a^2} + \frac{(y - k)^2}{b^2} = 1\), where \((h, k)\) is the center of the ellipse.
From the given equation \(\frac{(x - 3)^2}{4} + \frac{(y + 1)^2}{16} = 1\), determine the center as \((3, -1)\).
Compare the denominators to find \(a^2\) and \(b^2\). Here, \(a^2 = 16\) and \(b^2 = 4\). Since \(a^2 > b^2\), the major axis is vertical.
Calculate the distance \(c\) from the center to each focus using the formula \(c = \sqrt{a^2 - b^2}\).
Locate the foci at \((h, k \pm c)\) because the major axis is vertical, so the foci lie above and below the center along the y-axis.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Standard Form of an Ellipse
The standard form of an ellipse equation is (x - h)²/a² + (y - k)²/b² = 1, where (h, k) is the center. The values a² and b² represent the squares of the lengths of the semi-major and semi-minor axes. Understanding this form helps in identifying the ellipse's size, shape, and position on the coordinate plane.
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Major and Minor Axes
The major axis is the longest diameter of the ellipse, while the minor axis is the shortest. The larger denominator (a² or b²) corresponds to the major axis. Knowing which axis is major or minor is essential for graphing the ellipse accurately and determining the orientation (horizontal or vertical).
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Foci of an Ellipse
The foci are two fixed points inside the ellipse such that the sum of distances from any point on the ellipse to the foci is constant. Their locations are found using c² = |a² - b²|, where c is the distance from the center to each focus along the major axis. Identifying the foci is crucial for understanding the ellipse's geometric properties.
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Related Practice
Textbook Question
Textbook Question
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. x2 - 2x - 4y + 9 =0
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Textbook Question
Find the standard form of the equation of the parabola satisfying the given conditions. Focus: (12,0); Directrix: x=-12
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Textbook Question
Find the standard form of the equation of the parabola satisfying the given conditions. Focus: (0,-11); Directrix: y=11
Textbook Question
Use the center, vertices, and asymptotes to graph each hyperbola. Locate the foci and find the equations of the asymptotes. (x−1)2−(y−2)2=3
Textbook Question
Graph each ellipse and give the location of its foci. x²/25 + (y -2)² /36= 1
