(1)a=c/e=5,b^2=a^2-c^2=16
x^2/16+y^2/25=1
(2)x^2/9+y^2/4=1
(3)c=a*e=6,b^2=a^2-c^2=64
x^2/100+y^2/64=1或x^2/64+y^2/100=1
(4)c=a*e=2,b^2=32
x^2/36+y^2/32=1
(1)a=c/e=5,b^2=a^2-c^2=16
x^2/16+y^2/25=1
(2)x^2/9+y^2/4=1
(3)c=a*e=6,b^2=a^2-c^2=64
x^2/100+y^2/64=1或x^2/64+y^2/100=1
(4)c=a*e=2,b^2=32
x^2/36+y^2/32=1