Identify the property shared by all points (x,y)(x, y)(x,y) that satisfy the equation 9x2+4y2=369x^2 + 4y^2 = 369x2+4y2=36.
They form a circle with radius 6.
They are equidistant from the point (0,0)(0,0)(0,0) and the line x=4x=4x=4.
The difference of their distances from (0,13)(0, \sqrt{13})(0,13) and (0,−13)(0, -\sqrt{13})(0,−13) is constant at 4.
The sum of their distances from (5,0)(\sqrt{5}, 0)(5,0) and (−5,0)(-\sqrt{5}, 0)(−5,0) is constant at 6.