Question

若直线y=kx+2与双曲线x^2-y^2=6仅有一个公共点,则k

Answer 1

Y=KX+2 Y^2=K^2X^2+4+4KX

Y^2=X^2-6

X^2-6=K^2X^2+4KX+4

(K^2-1)X^2+4KX+10=0

△=0

16k^2-40k^2+40=0

24k^2=40

k=±根号15/3