x^2/9-y^2/4=1
a^2=9,b^2=4,c^2=9+4=13
e=c/a=根号13/3
PF2=3,则有|PF1-PF2|=2a=6
故有PF1=9,设P到左准线的距离是d,则有e=PF1/d
d=PF1/e=9/(根号13/3)=27/根号13=27/13*根号13