以BC中点为原点O,BC为X轴建立平面直角坐标系.则A,G,O共线,延长BG交AC于D,延长CG交AB于E,则BD=3BG/2 CE=3CG/2BD+CE=3（BG+CG）/2=30则BG+CG=20,显然G的轨迹是椭圆,则a=10 ,B(-8,0) C(8,0)则c^2=64 b^2=36所以x^2/100+...