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jmc

algebra senior

Problem

An ellipse has foci and , and it passes through the point Given this, we can write the equation of the ellipse in standard form as where are constants, and and are positive. Find the ordered quadruple .

(Enter your answer as an ordered list, for example, "1, 3, -9, 2".)
Solution
The sum of the distances from to the two foci is Therefore, the major axis has length Since the distance between the foci is it follows that the length of the minor axis is

The center of the ellipse is the midpoint of the segment between the foci, which is Since the foci and the center have the same -coordinate, the major axis is parallel to the -axis, and the minor axis is parallel to the -axis. Putting all this together, we get the equation of the ellipse: Thus,
Final answer
(8\sqrt3, 14, 2, 4)