y=-2√(3-x^2)<=0
y^2=4(3-x^2)
y^2+4x^2=12
此为下半平面的椭圆(因为y<=0)
y+2√(3-x^2)=0 2√(3-x^2)≥0, 0≥y
(y/2)^2+x^2=3
y^2/12+x^2/3=1
a=2√3,b=√3焦点在y轴,y≤0半幅椭圆
y=x^2-2根号3
这个是开口向上,对称轴是y轴的二次函数啊
y=-2√(3-x^2 )
Y^2=4(3-x^2)=12-4x^2
4x^2+y^2=12
X^2/3+y^2/12=1
又y<=0
所以是下半平面的椭圆