c = 2
2a = √[(0 - 3/2)^2 + (2 - 5/2)^2] + √[(0 - 3/2)^2 + (-2 - 5/2)^2]
= √(10/4]) + √ (90/4)
= 2√10
所以 a = √10
即 b = √(10 - 4)
= √6
所以 椭圆 的方程为 x^2/6 + y^2/10 = 1