已知双曲线kx^2+(5-k)y^2=k+3的焦点在y轴上,则k的取值范围
问题描述：
已知双曲线kx^2+(5-k)y^2=k+3的焦点在y轴上,则k的取值范围
答
焦点在y轴
则y²/[(k+3)/(5-k)]-x²[-(k+3)/k]=1
所以(k+3)/(5-k)>0
-(k+3)/k>0
即(k+3)(k-5)k(k+3)-3