设动圆的圆心为O(x，y)√[(x + 3)^2+ y^2] - 2 = 10 - √[(x - 3)^2+ y^2 ] = 动圆的半径化简得：3 x^2 + 4 y^2 = 108即圆心的轨迹方程为椭圆：x^2 / 36 + y^2 / 27 = 1
