设椭圆方程为：x^2/a^2+y^2/b^2=1,
4/a^2+(1/2)/b^2=1,(1)
2/a^2+3/4/b^2=1,(2)
(2)*2-(1)式,
1/b^2=1,
b^2=1,
代（2）式,
2/a^2+3/4=1,
2/a^2=1/4,
a^2=8,
∴椭圆方程为：x^2/8+y^2=1.