x^2/a^2+y^2/b^2=1
a^2=b^2+4
x^2/(b^2+4)+y^2/b^2=1
将p代人椭圆
9/(b^2+4)+24/b^2=1
两边乘b^2(b^2+4)
9b^2+24b^2+96=b^4+4b^2
b^4-29b^2-96=0
(b^2-32)(b^2+3)=0
b^2=32
a^2=36
x^2/36+y^2/32=1