过点A(1,0)的直线与双曲线x²/25-y²/4=1两支都相交,求直线l的斜率k的范围
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![过点A(1,0)的直线与双曲线x²/25-y²/4=1两支都相交,求直线l的斜率k的范围](/uploads/image/z/10196017-25-7.jpg?t=%E8%BF%87%E7%82%B9A%281%2C0%29%E7%9A%84%E7%9B%B4%E7%BA%BF%E4%B8%8E%E5%8F%8C%E6%9B%B2%E7%BA%BFx%26%23178%3B%2F25-y%26%23178%3B%2F4%3D1%E4%B8%A4%E6%94%AF%E9%83%BD%E7%9B%B8%E4%BA%A4%2C%E6%B1%82%E7%9B%B4%E7%BA%BFl%E7%9A%84%E6%96%9C%E7%8E%87k%E7%9A%84%E8%8C%83%E5%9B%B4)
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过点A(1,0)的直线与双曲线x²/25-y²/4=1两支都相交,求直线l的斜率k的范围
过点A(1,0)的直线与双曲线x²/25-y²/4=1两支都相交,求直线l的斜率k的范围
过点A(1,0)的直线与双曲线x²/25-y²/4=1两支都相交,求直线l的斜率k的范围
联立方程组即可
设直线为y=k(x-1)
与双曲线方程x²/25-y²/4=1联立
则 4x²-25k²(x-1)²=100
即 (4-25k²)x²+50k²x-(25k²+100)=0(**)
由已知,直线与双曲线交于两支,
∴ 方程(**)有两个异号实根
∴ 4-25k²和-(25k²+100)异号
∵ -(25k²+100)恒负
∴ 4-25k²>0
∴ 25k²