liulibiao
春芽
共回答了20个问题采纳率:90% 举报
(1)
c=√15,
F1(-√15,0),F2(√15,0)
2a=|MF1|+|MF2|
=√[(4+√15)²+1]+√[(4-√15)²+1]
=√(32-8√15)+√(32+4√15)
=(2√5-2√3)+(2√5+2√3)
=4√5
a=2√5,b^2=a^2-c^2=5
椭圆C:x^2/20+y^2/5=1
{x-y+m=0
{x^2+4y^2=20
==>
x^2+4(x+m)²-20=0
==>
5x²+8mx+4m²-20=0
Δ=64m²-20(4m²-20)>0
m²
1年前
5