Math Problem Statement

Find an equation for the conic whose graph is shown. The x y-coordinate plane is given. The curve enters the window in the third quadrant, goes up and right becoming less steep, crosses the x-axis at x = −1, changes direction at the point (0, 5), goes down and right becoming more steep, crosses the x-axis at x = 1, and exits the window in the fourth quadrant.

Solution

The description given matches the graph of a vertical ellipse. An ellipse has a symmetric, oval shape, and the curve you describe intersects the x-axis at two points, which suggests it is centered at the origin. Additionally, since the curve reaches a maximum height at (0,5)(0, 5) and intersects the x-axis symmetrically, the center of this ellipse is indeed at the origin, and the major axis is vertical.

Steps to Determine the Equation

  1. Identify the Center and Orientation:
    The center of the ellipse is at the origin (0,0)(0, 0), and it has a vertical major axis (since it peaks at (0,5)(0, 5)).

  2. Determine the Semi-Major and Semi-Minor Axes:

    • The maximum height occurs at (0,5)(0, 5), so the semi-major axis length is a=5a = 5.
    • The ellipse crosses the x-axis at x=1x = -1 and x=1x = 1, giving a semi-minor axis length of b=1b = 1.
  3. Formulate the Equation:
    For an ellipse centered at (0,0)(0, 0) with a vertical major axis, the equation is: x2b2+y2a2=1\frac{x^2}{b^2} + \frac{y^2}{a^2} = 1 Substituting a=5a = 5 and b=1b = 1 gives: x212+y252=1\frac{x^2}{1^2} + \frac{y^2}{5^2} = 1 Simplifying, we get: x2+y225=1x^2 + \frac{y^2}{25} = 1

Final Equation

The equation for the ellipse is: x2+y225=1x^2 + \frac{y^2}{25} = 1

Would you like a detailed breakdown or have any questions?


  1. How can you distinguish between ellipses and other conics like parabolas and hyperbolas?
  2. What changes in the equation if the ellipse is centered at a different point, say (h,k)(h, k)?
  3. How do the semi-major and semi-minor axes affect the shape of an ellipse?
  4. Can this equation be converted into a parametric form? How?
  5. What would happen to the ellipse if the semi-minor axis were increased?

Tip: For any conic section, observing the intercepts and symmetry helps in identifying its type and orientation.

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Math Problem Analysis

Mathematical Concepts

Analytic Geometry
Conic Sections
Ellipses

Formulas

Equation of an ellipse with vertical major axis: (x^2 / b^2) + (y^2 / a^2) = 1
Standard form of a conic centered at (h, k): ((x - h)^2 / b^2) + ((y - k)^2 / a^2) = 1

Theorems

Symmetry properties of ellipses
Definitions of major and minor axes

Suitable Grade Level

Grades 10-12