x^2/4-y^2=1
a^2=4,b^2=1,c^2=4+1=5.
焦点相同,则椭圆c^2=5
e=c/a=根号5/3,c^2/a^2=5/9
故a^2=9
b^2=a^2-c^2=9-5=4
故椭圆方程x^2/9+y^2/4=1