The circles.......................that form that ellipse.............are centered at - 1/2 and 1/2 on the X axis.......both of their edges hit the other circle's center................................the overlap forms the ellipse..........which is centered at the origin.......................the circles have a radius of 1....both of them...........................................they would have to go from 1/2 to - 1/2 or the other way..................so the X intercepts are (-1/2, 0) and (1/2, 0)...........or in decimals...............( - 0.5, 0).........and ( 0.5, 0)...............looks like an inverted......5050........the sum of the 1st 100 numbers..........