(mx)^2+(ny)^2=-mn两端同除以-mn得x^2/(-n/m)+y^2/(-m/n)=1若｜m｜>n,则焦点在Y轴上,c^2=(-m/n)-(-n/m)=(m^2-n^2)/(-mn),焦点坐标为（0,√[(m^2-n^2)/(-mn)]),（0,-√[(m^2-n^2)/(-mn)])若｜m｜...