设：x^2/a^2+y^2/b^2=1
则有：
a^2-b^2=2^2````````````````````````1
25b^2/4+9a^2/4=a^2b^2`````````2
联立1、2解得：
a^2=10,b^2=6
所以：椭圆的方程x^2/10+y^2/6=1