Question 815227
Find the equation of the graph of all points such that the sum of the distances from (1,0,0) and (-1,0,0) is always equal to 4.  Describe the graph.
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In the x-y plane it's the ellipse {{{x^2/4 + y^2/3 = 1}}}
In 3-space it's the ellipsoid of revolution with its axis of revolution the x-axis.
{{{x^2/4 + y^2/3 + z^2/3 = 1}}}