将y=kx+1代入双曲线x²-y²=1中,得:
x²-(kx+1)²=1
x²-(k²x²+2kx+1)=1
(1-k²)x²-2kx-2=0
(k²-1)x²+2kx+2=0
则:
①△=(2k)²-8(k²-1)=8-4k²≥0,得:-√2≤k≤√2
②x1x2=2/(k²-1)
将y=kx+1代入双曲线x²-y²=1中,得:
x²-(kx+1)²=1
x²-(k²x²+2kx+1)=1
(1-k²)x²-2kx-2=0
(k²-1)x²+2kx+2=0
则:
①△=(2k)²-8(k²-1)=8-4k²≥0,得:-√2≤k≤√2
②x1x2=2/(k²-1)