RADIO TELESCOPES The cross-section of a large radio telescope is a parabola. The dish is set into the ground. The equation that describes the cross-section is d = x2 + 2x - 8 , where d gives the depth of the dish below
ground and x is the distance from the control center, both in meters. If the dish does not extend above the ground level,
what is the diameter of the dish? Solve by graphing.