Question

椭圆x²/16+y²/m=1的离心率为1/3,则m的值为?

Answer 1

1.a^2=16 a=4

e=c/a=1/3 a=3c c=4/3 m=b^2=a^2-c^2=8c^2=128/9

2.b^2=16 a^2=m

e=c/a=1/3 c^2/m=1/9 m=9c^2

m=16+c^2 c^2=2 m=b^2+c^2=18